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https://github.com/git/git
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f48fd68887
This adds "attribute macros" (for lack of better name). So far, we have low-level attributes such as crlf and diff, which are defined in operational terms --- setting or unsetting them on a particular path directly affects what is done to the path. For example, in order to decline diffs or crlf conversions on a binary blob, no diffs on PostScript files, and treat all other files normally, you would have something like these: * diff crlf *.ps !diff proprietary.o !diff !crlf That is fine as the operation goes, but gets unwieldy rather rapidly, when we start adding more low-level attributes that are defined in operational terms. A near-term example of such an attribute would be 'merge-3way' which would control if git should attempt the usual 3-way file-level merge internally, or leave merging to a specialized external program of user's choice. When it is added, we do _not_ want to force the users to update the above to: * diff crlf merge-3way *.ps !diff proprietary.o !diff !crlf !merge-3way The way this patch solves this issue is to realize that the attributes the user is assigning to paths are not defined in terms of operations but in terms of what they are. All of the three low-level attributes usually make sense for most of the files that sane SCM users have git operate on (these files are typically called "text'). Only a few cases, such as binary blob, need exception to decline the "usual treatment given to text files" -- and people mark them as "binary". So this allows the $GIT_DIR/info/alternates and .gitattributes at the toplevel of the project to also specify attributes that assigns other attributes. The syntax is '[attr]' followed by an attribute name followed by a list of attribute names: [attr] binary !diff !crlf !merge-3way When "binary" attribute is set to a path, if the path has not got diff/crlf/merge-3way attribute set or unset by other rules, this rule unsets the three low-level attributes. It is expected that the user level .gitattributes will be expressed mostly in terms of attributes based on what the files are, and the above sample would become like this: (built-in attribute configuration) [attr] binary !diff !crlf !merge-3way * diff crlf merge-3way (project specific .gitattributes) proprietary.o binary (user preference $GIT_DIR/info/attributes) *.ps !diff There are a few caveats. * As described above, you can define these macros only in $GIT_DIR/info/attributes and toplevel .gitattributes. * There is no attempt to detect circular definition of macro attributes, and definitions are evaluated from bottom to top as usual to fill in other attributes that have not yet got values. The following would work as expected: [attr] text diff crlf [attr] ps text !diff *.ps ps while this would most likely not (I haven't tried): [attr] ps text !diff [attr] text diff crlf *.ps ps * When a macro says "[attr] A B !C", saying that a path does not have attribute A does not let you tell anything about attributes B or C. That is, given this: [attr] text diff crlf [attr] ps text !diff *.txt !ps path hello.txt, which would match "*.txt" pattern, would have "ps" attribute set to zero, but that does not make text attribute of hello.txt set to false (nor diff attribute set to true). Signed-off-by: Junio C Hamano <junkio@cox.net>
464 lines
11 KiB
C
464 lines
11 KiB
C
#include "cache.h"
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#include "attr.h"
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/*
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* The basic design decision here is that we are not going to have
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* insanely large number of attributes.
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*
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* This is a randomly chosen prime.
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*/
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#define HASHSIZE 257
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#ifndef DEBUG_ATTR
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#define DEBUG_ATTR 0
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#endif
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struct git_attr {
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struct git_attr *next;
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unsigned h;
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int attr_nr;
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char name[FLEX_ARRAY];
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};
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static int attr_nr;
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static struct git_attr_check *check_all_attr;
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static struct git_attr *(git_attr_hash[HASHSIZE]);
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static unsigned hash_name(const char *name, int namelen)
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{
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unsigned val = 0;
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unsigned char c;
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while (namelen--) {
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c = *name++;
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val = ((val << 7) | (val >> 22)) ^ c;
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}
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return val;
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}
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struct git_attr *git_attr(const char *name, int len)
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{
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unsigned hval = hash_name(name, len);
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unsigned pos = hval % HASHSIZE;
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struct git_attr *a;
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for (a = git_attr_hash[pos]; a; a = a->next) {
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if (a->h == hval &&
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!memcmp(a->name, name, len) && !a->name[len])
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return a;
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}
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a = xmalloc(sizeof(*a) + len + 1);
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memcpy(a->name, name, len);
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a->name[len] = 0;
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a->h = hval;
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a->next = git_attr_hash[pos];
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a->attr_nr = attr_nr++;
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git_attr_hash[pos] = a;
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check_all_attr = xrealloc(check_all_attr,
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sizeof(*check_all_attr) * attr_nr);
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check_all_attr[a->attr_nr].attr = a;
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return a;
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}
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/*
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* .gitattributes file is one line per record, each of which is
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*
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* (1) glob pattern.
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* (2) whitespace
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* (3) whitespace separated list of attribute names, each of which
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* could be prefixed with '!' to mean "not set".
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*/
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struct attr_state {
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int unset;
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struct git_attr *attr;
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};
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struct match_attr {
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union {
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char *pattern;
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struct git_attr *attr;
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} u;
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char is_macro;
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unsigned num_attr;
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struct attr_state state[FLEX_ARRAY];
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};
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static const char blank[] = " \t\r\n";
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static struct match_attr *parse_attr_line(const char *line, const char *src,
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int lineno, int macro_ok)
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{
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int namelen;
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int num_attr;
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const char *cp, *name;
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struct match_attr *res = res;
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int pass;
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int is_macro;
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cp = line + strspn(line, blank);
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if (!*cp || *cp == '#')
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return NULL;
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name = cp;
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namelen = strcspn(name, blank);
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if (strlen(ATTRIBUTE_MACRO_PREFIX) < namelen &&
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!prefixcmp(name, ATTRIBUTE_MACRO_PREFIX)) {
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if (!macro_ok) {
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fprintf(stderr, "%s not allowed: %s:%d\n",
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name, src, lineno);
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return NULL;
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}
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is_macro = 1;
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name += strlen(ATTRIBUTE_MACRO_PREFIX);
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name += strspn(name, blank);
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namelen = strcspn(name, blank);
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}
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else
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is_macro = 0;
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for (pass = 0; pass < 2; pass++) {
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/* pass 0 counts and allocates, pass 1 fills */
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num_attr = 0;
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cp = name + namelen;
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cp = cp + strspn(cp, blank);
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while (*cp) {
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const char *ep;
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ep = cp + strcspn(cp, blank);
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if (pass) {
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struct attr_state *e;
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e = &(res->state[num_attr]);
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if (*cp == '!') {
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e->unset = 1;
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cp++;
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}
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e->attr = git_attr(cp, ep - cp);
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}
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num_attr++;
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cp = ep + strspn(ep, blank);
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}
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if (pass)
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break;
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res = xcalloc(1,
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sizeof(*res) +
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sizeof(struct attr_state) * num_attr +
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(is_macro ? 0 : namelen + 1));
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if (is_macro)
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res->u.attr = git_attr(name, namelen);
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else {
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res->u.pattern = (char*)&(res->state[num_attr]);
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memcpy(res->u.pattern, name, namelen);
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res->u.pattern[namelen] = 0;
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}
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res->is_macro = is_macro;
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res->num_attr = num_attr;
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}
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return res;
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}
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/*
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* Like info/exclude and .gitignore, the attribute information can
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* come from many places.
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*
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* (1) .gitattribute file of the same directory;
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* (2) .gitattribute file of the parent directory if (1) does not have any match;
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* this goes recursively upwards, just like .gitignore
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* (3) perhaps $GIT_DIR/info/attributes, as the final fallback.
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*
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* In the same file, later entries override the earlier match, so in the
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* global list, we would have entries from info/attributes the earliest
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* (reading the file from top to bottom), .gitattribute of the root
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* directory (again, reading the file from top to bottom) down to the
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* current directory, and then scan the list backwards to find the first match.
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* This is exactly the same as what excluded() does in dir.c to deal with
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* .gitignore
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*/
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static struct attr_stack {
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struct attr_stack *prev;
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char *origin;
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unsigned num_matches;
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struct match_attr **attrs;
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} *attr_stack;
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static void free_attr_elem(struct attr_stack *e)
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{
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int i;
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free(e->origin);
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for (i = 0; i < e->num_matches; i++)
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free(e->attrs[i]);
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free(e);
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}
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static const char *builtin_attr[] = {
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NULL,
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};
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static struct attr_stack *read_attr_from_array(const char **list)
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{
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struct attr_stack *res;
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const char *line;
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int lineno = 0;
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res = xcalloc(1, sizeof(*res));
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while ((line = *(list++)) != NULL) {
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struct match_attr *a;
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a = parse_attr_line(line, "[builtin]", ++lineno, 1);
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if (!a)
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continue;
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res->attrs = xrealloc(res->attrs, res->num_matches + 1);
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res->attrs[res->num_matches++] = a;
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}
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return res;
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}
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static struct attr_stack *read_attr_from_file(const char *path, int macro_ok)
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{
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FILE *fp;
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struct attr_stack *res;
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char buf[2048];
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int lineno = 0;
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res = xcalloc(1, sizeof(*res));
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fp = fopen(path, "r");
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if (!fp)
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return res;
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while (fgets(buf, sizeof(buf), fp)) {
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struct match_attr *a;
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a = parse_attr_line(buf, path, ++lineno, macro_ok);
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if (!a)
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continue;
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res->attrs = xrealloc(res->attrs, res->num_matches + 1);
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res->attrs[res->num_matches++] = a;
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}
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fclose(fp);
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return res;
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}
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#if DEBUG_ATTR
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static void debug_info(const char *what, struct attr_stack *elem)
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{
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fprintf(stderr, "%s: %s\n", what, elem->origin ? elem->origin : "()");
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}
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static void debug_set(const char *what, const char *match, struct git_attr *attr, int set)
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{
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fprintf(stderr, "%s: %s => %d (%s)\n",
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what, attr->name, set, match);
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}
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#define debug_push(a) debug_info("push", (a))
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#define debug_pop(a) debug_info("pop", (a))
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#else
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#define debug_push(a) do { ; } while (0)
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#define debug_pop(a) do { ; } while (0)
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#define debug_set(a,b,c,d) do { ; } while (0)
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#endif
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static void bootstrap_attr_stack(void)
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{
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if (!attr_stack) {
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struct attr_stack *elem;
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elem = read_attr_from_array(builtin_attr);
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elem->origin = NULL;
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elem->prev = attr_stack;
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attr_stack = elem;
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elem = read_attr_from_file(GITATTRIBUTES_FILE, 1);
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elem->origin = strdup("");
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elem->prev = attr_stack;
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attr_stack = elem;
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debug_push(elem);
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elem = read_attr_from_file(git_path(INFOATTRIBUTES_FILE), 1);
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elem->origin = NULL;
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elem->prev = attr_stack;
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attr_stack = elem;
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}
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}
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static void prepare_attr_stack(const char *path, int dirlen)
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{
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struct attr_stack *elem, *info;
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int len;
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char pathbuf[PATH_MAX];
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/*
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* At the bottom of the attribute stack is the built-in
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* set of attribute definitions. Then, contents from
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* .gitattribute files from directories closer to the
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* root to the ones in deeper directories are pushed
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* to the stack. Finally, at the very top of the stack
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* we always keep the contents of $GIT_DIR/info/attributes.
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*
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* When checking, we use entries from near the top of the
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* stack, preferring $GIT_DIR/info/attributes, then
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* .gitattributes in deeper directories to shallower ones,
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* and finally use the built-in set as the default.
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*/
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if (!attr_stack)
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bootstrap_attr_stack();
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/*
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* Pop the "info" one that is always at the top of the stack.
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*/
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info = attr_stack;
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attr_stack = info->prev;
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/*
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* Pop the ones from directories that are not the prefix of
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* the path we are checking.
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*/
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while (attr_stack && attr_stack->origin) {
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int namelen = strlen(attr_stack->origin);
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elem = attr_stack;
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if (namelen <= dirlen &&
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!strncmp(elem->origin, path, namelen))
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break;
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debug_pop(elem);
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attr_stack = elem->prev;
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free_attr_elem(elem);
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}
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/*
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* Read from parent directories and push them down
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*/
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while (1) {
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char *cp;
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len = strlen(attr_stack->origin);
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if (dirlen <= len)
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break;
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memcpy(pathbuf, path, dirlen);
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memcpy(pathbuf + dirlen, "/", 2);
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cp = strchr(pathbuf + len + 1, '/');
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strcpy(cp + 1, GITATTRIBUTES_FILE);
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elem = read_attr_from_file(pathbuf, 0);
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*cp = '\0';
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elem->origin = strdup(pathbuf);
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elem->prev = attr_stack;
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attr_stack = elem;
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debug_push(elem);
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}
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/*
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* Finally push the "info" one at the top of the stack.
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*/
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info->prev = attr_stack;
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attr_stack = info;
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}
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static int path_matches(const char *pathname, int pathlen,
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const char *pattern,
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const char *base, int baselen)
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{
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if (!strchr(pattern, '/')) {
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/* match basename */
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const char *basename = strrchr(pathname, '/');
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basename = basename ? basename + 1 : pathname;
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return (fnmatch(pattern, basename, 0) == 0);
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}
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/*
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* match with FNM_PATHNAME; the pattern has base implicitly
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* in front of it.
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*/
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if (*pattern == '/')
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pattern++;
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if (pathlen < baselen ||
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(baselen && pathname[baselen - 1] != '/') ||
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strncmp(pathname, base, baselen))
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return 0;
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return fnmatch(pattern, pathname + baselen, FNM_PATHNAME) == 0;
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}
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static int fill(const char *path, int pathlen, struct attr_stack *stk, int rem)
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{
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const char *base = stk->origin ? stk->origin : "";
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int i, j;
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struct git_attr_check *check = check_all_attr;
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for (i = stk->num_matches - 1; 0 < rem && 0 <= i; i--) {
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struct match_attr *a = stk->attrs[i];
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if (a->is_macro)
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continue;
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if (path_matches(path, pathlen,
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a->u.pattern, base, strlen(base))) {
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for (j = 0; 0 < rem && j < a->num_attr; j++) {
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struct git_attr *attr = a->state[j].attr;
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int set = !a->state[j].unset;
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int *n = &(check[attr->attr_nr].isset);
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if (*n < 0) {
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debug_set("fill", a->u.pattern, attr, set);
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*n = set;
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rem--;
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}
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}
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}
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}
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return rem;
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}
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static int macroexpand(struct attr_stack *stk, int rem)
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{
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int i, j;
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struct git_attr_check *check = check_all_attr;
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for (i = stk->num_matches - 1; 0 < rem && 0 <= i; i--) {
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struct match_attr *a = stk->attrs[i];
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if (!a->is_macro)
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continue;
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if (check[a->u.attr->attr_nr].isset < 0)
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continue;
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for (j = 0; 0 < rem && j < a->num_attr; j++) {
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struct git_attr *attr = a->state[j].attr;
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int set = !a->state[j].unset;
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int *n = &(check[attr->attr_nr].isset);
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if (*n < 0) {
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debug_set("expand", a->u.attr->name, attr, set);
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*n = set;
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rem--;
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}
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}
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}
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return rem;
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}
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int git_checkattr(const char *path, int num, struct git_attr_check *check)
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{
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struct attr_stack *stk;
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const char *cp;
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int dirlen, pathlen, i, rem;
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bootstrap_attr_stack();
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for (i = 0; i < attr_nr; i++)
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check_all_attr[i].isset = -1;
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pathlen = strlen(path);
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cp = strrchr(path, '/');
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if (!cp)
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dirlen = 0;
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else
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dirlen = cp - path;
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prepare_attr_stack(path, dirlen);
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rem = attr_nr;
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for (stk = attr_stack; 0 < rem && stk; stk = stk->prev)
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rem = fill(path, pathlen, stk, rem);
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for (stk = attr_stack; 0 < rem && stk; stk = stk->prev)
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rem = macroexpand(stk, rem);
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for (i = 0; i < num; i++)
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check[i].isset = check_all_attr[check[i].attr->attr_nr].isset;
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return 0;
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}
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