git/convert.c
Andy Parkins c23290d528 Fix mishandling of $Id$ expanded in the repository copy in convert.c
If the repository contained an expanded ident keyword (i.e. $Id:XXXX$),
then the wrong bytes were discarded, and the Id keyword was not
expanded.  The fault was in convert.c:ident_to_worktree().

Previously, when a "$Id:" was found in the repository version,
ident_to_worktree() would search for the next "$" after this, and
discarded everything it found until then.  That was done with the loop:

    do {
        ch = *cp++;
        if (ch == '$')
            break;
        rem--;
    } while (rem);

The above loop left cp pointing one character _after_ the final "$"
(because of ch = *cp++).  This was different from the non-expanded case,
were cp is left pointing at the "$", and was different from the comment
which stated "discard up to but not including the closing $".  This
patch fixes that by making the loop:

    do {
        ch = *cp;
        if (ch == '$')
            break;
        cp++;
        rem--;
    } while (rem);

That is, cp is tested _then_ incremented.

This loop exits if it finds a "$" or if it runs out of bytes in the
source.  After this loop, if there was no closing "$" the expansion is
skipped, and the outer loop is allowed to continue leaving this
non-keyword as it was.  However, when the "$" is found, size is
corrected, before running the expansion:

    size -= (cp - src);

This is wrong; size is going to be corrected anyway after the expansion,
so there is no need to do it here.  This patch removes that redundant
correction.

To help find this bug, I heavily commented the routine; those comments
are included here as a bonus.

Signed-off-by: Andy Parkins <andyparkins@gmail.com>
Signed-off-by: Junio C Hamano <junkio@cox.net>
2007-05-26 01:12:43 -07:00

705 lines
15 KiB
C

#include "cache.h"
#include "attr.h"
#include "run-command.h"
/*
* convert.c - convert a file when checking it out and checking it in.
*
* This should use the pathname to decide on whether it wants to do some
* more interesting conversions (automatic gzip/unzip, general format
* conversions etc etc), but by default it just does automatic CRLF<->LF
* translation when the "auto_crlf" option is set.
*/
#define CRLF_GUESS (-1)
#define CRLF_BINARY 0
#define CRLF_TEXT 1
#define CRLF_INPUT 2
struct text_stat {
/* CR, LF and CRLF counts */
unsigned cr, lf, crlf;
/* These are just approximations! */
unsigned printable, nonprintable;
};
static void gather_stats(const char *buf, unsigned long size, struct text_stat *stats)
{
unsigned long i;
memset(stats, 0, sizeof(*stats));
for (i = 0; i < size; i++) {
unsigned char c = buf[i];
if (c == '\r') {
stats->cr++;
if (i+1 < size && buf[i+1] == '\n')
stats->crlf++;
continue;
}
if (c == '\n') {
stats->lf++;
continue;
}
if (c == 127)
/* DEL */
stats->nonprintable++;
else if (c < 32) {
switch (c) {
/* BS, HT, ESC and FF */
case '\b': case '\t': case '\033': case '\014':
stats->printable++;
break;
default:
stats->nonprintable++;
}
}
else
stats->printable++;
}
}
/*
* The same heuristics as diff.c::mmfile_is_binary()
*/
static int is_binary(unsigned long size, struct text_stat *stats)
{
if ((stats->printable >> 7) < stats->nonprintable)
return 1;
/*
* Other heuristics? Average line length might be relevant,
* as might LF vs CR vs CRLF counts..
*
* NOTE! It might be normal to have a low ratio of CRLF to LF
* (somebody starts with a LF-only file and edits it with an editor
* that adds CRLF only to lines that are added..). But do we
* want to support CR-only? Probably not.
*/
return 0;
}
static char *crlf_to_git(const char *path, const char *src, unsigned long *sizep, int action)
{
char *buffer, *dst;
unsigned long size, nsize;
struct text_stat stats;
if ((action == CRLF_BINARY) || !auto_crlf)
return NULL;
size = *sizep;
if (!size)
return NULL;
gather_stats(src, size, &stats);
/* No CR? Nothing to convert, regardless. */
if (!stats.cr)
return NULL;
if (action == CRLF_GUESS) {
/*
* We're currently not going to even try to convert stuff
* that has bare CR characters. Does anybody do that crazy
* stuff?
*/
if (stats.cr != stats.crlf)
return NULL;
/*
* And add some heuristics for binary vs text, of course...
*/
if (is_binary(size, &stats))
return NULL;
}
/*
* Ok, allocate a new buffer, fill it in, and return it
* to let the caller know that we switched buffers.
*/
nsize = size - stats.crlf;
buffer = xmalloc(nsize);
*sizep = nsize;
dst = buffer;
if (action == CRLF_GUESS) {
/*
* If we guessed, we already know we rejected a file with
* lone CR, and we can strip a CR without looking at what
* follow it.
*/
do {
unsigned char c = *src++;
if (c != '\r')
*dst++ = c;
} while (--size);
} else {
do {
unsigned char c = *src++;
if (! (c == '\r' && (1 < size && *src == '\n')))
*dst++ = c;
} while (--size);
}
return buffer;
}
static char *crlf_to_worktree(const char *path, const char *src, unsigned long *sizep, int action)
{
char *buffer, *dst;
unsigned long size, nsize;
struct text_stat stats;
unsigned char last;
if ((action == CRLF_BINARY) || (action == CRLF_INPUT) ||
auto_crlf <= 0)
return NULL;
size = *sizep;
if (!size)
return NULL;
gather_stats(src, size, &stats);
/* No LF? Nothing to convert, regardless. */
if (!stats.lf)
return NULL;
/* Was it already in CRLF format? */
if (stats.lf == stats.crlf)
return NULL;
if (action == CRLF_GUESS) {
/* If we have any bare CR characters, we're not going to touch it */
if (stats.cr != stats.crlf)
return NULL;
if (is_binary(size, &stats))
return NULL;
}
/*
* Ok, allocate a new buffer, fill it in, and return it
* to let the caller know that we switched buffers.
*/
nsize = size + stats.lf - stats.crlf;
buffer = xmalloc(nsize);
*sizep = nsize;
last = 0;
dst = buffer;
do {
unsigned char c = *src++;
if (c == '\n' && last != '\r')
*dst++ = '\r';
*dst++ = c;
last = c;
} while (--size);
return buffer;
}
static int filter_buffer(const char *path, const char *src,
unsigned long size, const char *cmd)
{
/*
* Spawn cmd and feed the buffer contents through its stdin.
*/
struct child_process child_process;
int pipe_feed[2];
int write_err, status;
memset(&child_process, 0, sizeof(child_process));
if (pipe(pipe_feed) < 0) {
error("cannot create pipe to run external filter %s", cmd);
return 1;
}
child_process.pid = fork();
if (child_process.pid < 0) {
error("cannot fork to run external filter %s", cmd);
close(pipe_feed[0]);
close(pipe_feed[1]);
return 1;
}
if (!child_process.pid) {
dup2(pipe_feed[0], 0);
close(pipe_feed[0]);
close(pipe_feed[1]);
execlp("sh", "sh", "-c", cmd, NULL);
return 1;
}
close(pipe_feed[0]);
write_err = (write_in_full(pipe_feed[1], src, size) < 0);
if (close(pipe_feed[1]))
write_err = 1;
if (write_err)
error("cannot feed the input to external filter %s", cmd);
status = finish_command(&child_process);
if (status)
error("external filter %s failed %d", cmd, -status);
return (write_err || status);
}
static char *apply_filter(const char *path, const char *src,
unsigned long *sizep, const char *cmd)
{
/*
* Create a pipeline to have the command filter the buffer's
* contents.
*
* (child --> cmd) --> us
*/
const int SLOP = 4096;
int pipe_feed[2];
int status;
char *dst;
unsigned long dstsize, dstalloc;
struct child_process child_process;
if (!cmd)
return NULL;
memset(&child_process, 0, sizeof(child_process));
if (pipe(pipe_feed) < 0) {
error("cannot create pipe to run external filter %s", cmd);
return NULL;
}
fflush(NULL);
child_process.pid = fork();
if (child_process.pid < 0) {
error("cannot fork to run external filter %s", cmd);
close(pipe_feed[0]);
close(pipe_feed[1]);
return NULL;
}
if (!child_process.pid) {
dup2(pipe_feed[1], 1);
close(pipe_feed[0]);
close(pipe_feed[1]);
exit(filter_buffer(path, src, *sizep, cmd));
}
close(pipe_feed[1]);
dstalloc = *sizep;
dst = xmalloc(dstalloc);
dstsize = 0;
while (1) {
ssize_t numread = xread(pipe_feed[0], dst + dstsize,
dstalloc - dstsize);
if (numread <= 0) {
if (!numread)
break;
error("read from external filter %s failed", cmd);
free(dst);
dst = NULL;
break;
}
dstsize += numread;
if (dstalloc <= dstsize + SLOP) {
dstalloc = dstsize + SLOP;
dst = xrealloc(dst, dstalloc);
}
}
if (close(pipe_feed[0])) {
error("read from external filter %s failed", cmd);
free(dst);
dst = NULL;
}
status = finish_command(&child_process);
if (status) {
error("external filter %s failed %d", cmd, -status);
free(dst);
dst = NULL;
}
if (dst)
*sizep = dstsize;
return dst;
}
static struct convert_driver {
const char *name;
struct convert_driver *next;
char *smudge;
char *clean;
} *user_convert, **user_convert_tail;
static int read_convert_config(const char *var, const char *value)
{
const char *ep, *name;
int namelen;
struct convert_driver *drv;
/*
* External conversion drivers are configured using
* "filter.<name>.variable".
*/
if (prefixcmp(var, "filter.") || (ep = strrchr(var, '.')) == var + 6)
return 0;
name = var + 7;
namelen = ep - name;
for (drv = user_convert; drv; drv = drv->next)
if (!strncmp(drv->name, name, namelen) && !drv->name[namelen])
break;
if (!drv) {
char *namebuf;
drv = xcalloc(1, sizeof(struct convert_driver));
namebuf = xmalloc(namelen + 1);
memcpy(namebuf, name, namelen);
namebuf[namelen] = 0;
drv->name = namebuf;
drv->next = NULL;
*user_convert_tail = drv;
user_convert_tail = &(drv->next);
}
ep++;
/*
* filter.<name>.smudge and filter.<name>.clean specifies
* the command line:
*
* command-line
*
* The command-line will not be interpolated in any way.
*/
if (!strcmp("smudge", ep)) {
if (!value)
return error("%s: lacks value", var);
drv->smudge = strdup(value);
return 0;
}
if (!strcmp("clean", ep)) {
if (!value)
return error("%s: lacks value", var);
drv->clean = strdup(value);
return 0;
}
return 0;
}
static void setup_convert_check(struct git_attr_check *check)
{
static struct git_attr *attr_crlf;
static struct git_attr *attr_ident;
static struct git_attr *attr_filter;
if (!attr_crlf) {
attr_crlf = git_attr("crlf", 4);
attr_ident = git_attr("ident", 5);
attr_filter = git_attr("filter", 6);
user_convert_tail = &user_convert;
git_config(read_convert_config);
}
check[0].attr = attr_crlf;
check[1].attr = attr_ident;
check[2].attr = attr_filter;
}
static int count_ident(const char *cp, unsigned long size)
{
/*
* "$Id: 0000000000000000000000000000000000000000 $" <=> "$Id$"
*/
int cnt = 0;
char ch;
while (size) {
ch = *cp++;
size--;
if (ch != '$')
continue;
if (size < 3)
break;
if (memcmp("Id", cp, 2))
continue;
ch = cp[2];
cp += 3;
size -= 3;
if (ch == '$')
cnt++; /* $Id$ */
if (ch != ':')
continue;
/*
* "$Id: ... "; scan up to the closing dollar sign and discard.
*/
while (size) {
ch = *cp++;
size--;
if (ch == '$') {
cnt++;
break;
}
}
}
return cnt;
}
static char *ident_to_git(const char *path, const char *src, unsigned long *sizep, int ident)
{
int cnt;
unsigned long size;
char *dst, *buf;
if (!ident)
return NULL;
size = *sizep;
cnt = count_ident(src, size);
if (!cnt)
return NULL;
buf = xmalloc(size);
for (dst = buf; size; size--) {
char ch = *src++;
*dst++ = ch;
if ((ch == '$') && (3 <= size) &&
!memcmp("Id:", src, 3)) {
unsigned long rem = size - 3;
const char *cp = src + 3;
do {
ch = *cp++;
if (ch == '$')
break;
rem--;
} while (rem);
if (!rem)
continue;
memcpy(dst, "Id$", 3);
dst += 3;
size -= (cp - src);
src = cp;
}
}
*sizep = dst - buf;
return buf;
}
static char *ident_to_worktree(const char *path, const char *src, unsigned long *sizep, int ident)
{
int cnt;
unsigned long size;
char *dst, *buf;
unsigned char sha1[20];
if (!ident)
return NULL;
size = *sizep;
cnt = count_ident(src, size);
if (!cnt)
return NULL;
hash_sha1_file(src, size, "blob", sha1);
buf = xmalloc(size + cnt * 43);
for (dst = buf; size; size--) {
const char *cp;
/* Fetch next source character, move the pointer on */
char ch = *src++;
/* Copy the current character to the destination */
*dst++ = ch;
/* If the current character is "$" or there are less than three
* remaining bytes or the two bytes following this one are not
* "Id", then simply read the next character */
if ((ch != '$') || (size < 3) || memcmp("Id", src, 2))
continue;
/*
* Here when
* - There are more than 2 bytes remaining
* - The current three bytes are "$Id"
* with
* - ch == "$"
* - src[0] == "I"
*/
/*
* It's possible that an expanded Id has crept its way into the
* repository, we cope with that by stripping the expansion out
*/
if (src[2] == ':') {
/* Expanded keywords have "$Id:" at the front */
/* discard up to but not including the closing $ */
unsigned long rem = size - 3;
/* Point at first byte after the ":" */
cp = src + 3;
/*
* Throw away characters until either
* - we reach a "$"
* - we run out of bytes (rem == 0)
*/
do {
ch = *cp;
if (ch == '$')
break;
cp++;
rem--;
} while (rem);
/* If the above finished because it ran out of characters, then
* this is an incomplete keyword, so don't run the expansion */
if (!rem)
continue;
} else if (src[2] == '$')
cp = src + 2;
else
/* Anything other than "$Id:XXX$" or $Id$ and we skip the
* expansion */
continue;
/* cp is now pointing at the last $ of the keyword */
memcpy(dst, "Id: ", 4);
dst += 4;
memcpy(dst, sha1_to_hex(sha1), 40);
dst += 40;
*dst++ = ' ';
/* Adjust for the characters we've discarded */
size -= (cp - src);
src = cp;
/* Copy the final "$" */
*dst++ = *src++;
size--;
}
*sizep = dst - buf;
return buf;
}
static int git_path_check_crlf(const char *path, struct git_attr_check *check)
{
const char *value = check->value;
if (ATTR_TRUE(value))
return CRLF_TEXT;
else if (ATTR_FALSE(value))
return CRLF_BINARY;
else if (ATTR_UNSET(value))
;
else if (!strcmp(value, "input"))
return CRLF_INPUT;
return CRLF_GUESS;
}
static struct convert_driver *git_path_check_convert(const char *path,
struct git_attr_check *check)
{
const char *value = check->value;
struct convert_driver *drv;
if (ATTR_TRUE(value) || ATTR_FALSE(value) || ATTR_UNSET(value))
return NULL;
for (drv = user_convert; drv; drv = drv->next)
if (!strcmp(value, drv->name))
return drv;
return NULL;
}
static int git_path_check_ident(const char *path, struct git_attr_check *check)
{
const char *value = check->value;
return !!ATTR_TRUE(value);
}
char *convert_to_git(const char *path, const char *src, unsigned long *sizep)
{
struct git_attr_check check[3];
int crlf = CRLF_GUESS;
int ident = 0;
char *filter = NULL;
char *buf, *buf2;
setup_convert_check(check);
if (!git_checkattr(path, ARRAY_SIZE(check), check)) {
struct convert_driver *drv;
crlf = git_path_check_crlf(path, check + 0);
ident = git_path_check_ident(path, check + 1);
drv = git_path_check_convert(path, check + 2);
if (drv && drv->clean)
filter = drv->clean;
}
buf = apply_filter(path, src, sizep, filter);
buf2 = crlf_to_git(path, buf ? buf : src, sizep, crlf);
if (buf2) {
free(buf);
buf = buf2;
}
buf2 = ident_to_git(path, buf ? buf : src, sizep, ident);
if (buf2) {
free(buf);
buf = buf2;
}
return buf;
}
char *convert_to_working_tree(const char *path, const char *src, unsigned long *sizep)
{
struct git_attr_check check[3];
int crlf = CRLF_GUESS;
int ident = 0;
char *filter = NULL;
char *buf, *buf2;
setup_convert_check(check);
if (!git_checkattr(path, ARRAY_SIZE(check), check)) {
struct convert_driver *drv;
crlf = git_path_check_crlf(path, check + 0);
ident = git_path_check_ident(path, check + 1);
drv = git_path_check_convert(path, check + 2);
if (drv && drv->smudge)
filter = drv->smudge;
}
buf = ident_to_worktree(path, src, sizep, ident);
buf2 = crlf_to_worktree(path, buf ? buf : src, sizep, crlf);
if (buf2) {
free(buf);
buf = buf2;
}
buf2 = apply_filter(path, buf ? buf : src, sizep, filter);
if (buf2) {
free(buf);
buf = buf2;
}
return buf;
}
void *convert_sha1_file(const char *path, const unsigned char *sha1,
unsigned int mode, enum object_type *type,
unsigned long *size)
{
void *buffer = read_sha1_file(sha1, type, size);
if (S_ISREG(mode) && buffer) {
void *converted = convert_to_working_tree(path, buffer, size);
if (converted) {
free(buffer);
buffer = converted;
}
}
return buffer;
}