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https://github.com/git/git
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![Linus Torvalds](/assets/img/avatar_default.png)
This is another patch in the "prepare to do more in C" series, where the git wrapper command is taught about the notion of handling some functionality internally. Right now, the only internal commands are "version" and "help", but the point being that we can now easily extend it to handle some of the trivial scripts internally. Things like "git log" and "git diff" wouldn't need separate external scripts any more. This also implies that to support the old "git-log" and "git-diff" syntax, the "git" wrapper now automatically looks at the name it was executed as, and if it is "git-xxxx", it will assume that it is to internally do what "git xxxx" would do. In other words, you can (once you implement an internal command) soft- or hard-link that command to the "git" wrapper command, and it will do the right thing, whether you use the "git xxxx" or the "git-xxxx" format. There's one other change: the search order for external programs is modified slightly, so that the first entry remains GIT_EXEC_DIR, but the second entry is the same directory as the git wrapper itself was executed out of - if we can figure it out from argv[0], of course. Signed-off-by: Linus Torvalds <torvalds@osdl.org> Signed-off-by: Junio C Hamano <junkio@cox.net>
374 lines
7.6 KiB
C
374 lines
7.6 KiB
C
#include <stdio.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <dirent.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <string.h>
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#include <errno.h>
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#include <limits.h>
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#include <stdarg.h>
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#include <sys/ioctl.h>
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#include "git-compat-util.h"
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#include "exec_cmd.h"
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#ifndef PATH_MAX
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# define PATH_MAX 4096
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#endif
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static const char git_usage[] =
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"Usage: git [--version] [--exec-path[=GIT_EXEC_PATH]] [--help] COMMAND [ ARGS ]";
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/* most gui terms set COLUMNS (although some don't export it) */
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static int term_columns(void)
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{
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char *col_string = getenv("COLUMNS");
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int n_cols = 0;
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if (col_string && (n_cols = atoi(col_string)) > 0)
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return n_cols;
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#ifdef TIOCGWINSZ
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{
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struct winsize ws;
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if (!ioctl(1, TIOCGWINSZ, &ws)) {
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if (ws.ws_col)
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return ws.ws_col;
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}
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}
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#endif
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return 80;
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}
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static void oom(void)
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{
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fprintf(stderr, "git: out of memory\n");
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exit(1);
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}
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static inline void mput_char(char c, unsigned int num)
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{
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while(num--)
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putchar(c);
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}
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static struct cmdname {
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size_t len;
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char name[1];
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} **cmdname;
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static int cmdname_alloc, cmdname_cnt;
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static void add_cmdname(const char *name, int len)
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{
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struct cmdname *ent;
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if (cmdname_alloc <= cmdname_cnt) {
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cmdname_alloc = cmdname_alloc + 200;
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cmdname = realloc(cmdname, cmdname_alloc * sizeof(*cmdname));
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if (!cmdname)
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oom();
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}
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ent = malloc(sizeof(*ent) + len);
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if (!ent)
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oom();
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ent->len = len;
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memcpy(ent->name, name, len);
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ent->name[len] = 0;
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cmdname[cmdname_cnt++] = ent;
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}
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static int cmdname_compare(const void *a_, const void *b_)
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{
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struct cmdname *a = *(struct cmdname **)a_;
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struct cmdname *b = *(struct cmdname **)b_;
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return strcmp(a->name, b->name);
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}
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static void pretty_print_string_list(struct cmdname **cmdname, int longest)
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{
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int cols = 1, rows;
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int space = longest + 1; /* min 1 SP between words */
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int max_cols = term_columns() - 1; /* don't print *on* the edge */
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int i, j;
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if (space < max_cols)
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cols = max_cols / space;
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rows = (cmdname_cnt + cols - 1) / cols;
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qsort(cmdname, cmdname_cnt, sizeof(*cmdname), cmdname_compare);
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for (i = 0; i < rows; i++) {
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printf(" ");
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for (j = 0; j < cols; j++) {
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int n = j * rows + i;
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int size = space;
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if (n >= cmdname_cnt)
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break;
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if (j == cols-1 || n + rows >= cmdname_cnt)
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size = 1;
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printf("%-*s", size, cmdname[n]->name);
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}
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putchar('\n');
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}
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}
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static void list_commands(const char *exec_path, const char *pattern)
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{
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unsigned int longest = 0;
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char path[PATH_MAX];
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int dirlen;
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DIR *dir = opendir(exec_path);
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struct dirent *de;
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if (!dir) {
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fprintf(stderr, "git: '%s': %s\n", exec_path, strerror(errno));
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exit(1);
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}
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dirlen = strlen(exec_path);
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if (PATH_MAX - 20 < dirlen) {
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fprintf(stderr, "git: insanely long exec-path '%s'\n",
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exec_path);
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exit(1);
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}
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memcpy(path, exec_path, dirlen);
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path[dirlen++] = '/';
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while ((de = readdir(dir)) != NULL) {
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struct stat st;
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int entlen;
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if (strncmp(de->d_name, "git-", 4))
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continue;
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strcpy(path+dirlen, de->d_name);
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if (stat(path, &st) || /* stat, not lstat */
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!S_ISREG(st.st_mode) ||
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!(st.st_mode & S_IXUSR))
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continue;
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entlen = strlen(de->d_name);
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if (4 < entlen && !strcmp(de->d_name + entlen - 4, ".exe"))
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entlen -= 4;
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if (longest < entlen)
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longest = entlen;
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add_cmdname(de->d_name + 4, entlen-4);
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}
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closedir(dir);
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printf("git commands available in '%s'\n", exec_path);
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printf("----------------------------");
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mput_char('-', strlen(exec_path));
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putchar('\n');
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pretty_print_string_list(cmdname, longest - 4);
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putchar('\n');
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}
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#ifdef __GNUC__
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static void cmd_usage(const char *exec_path, const char *fmt, ...)
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__attribute__((__format__(__printf__, 2, 3), __noreturn__));
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#endif
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static void cmd_usage(const char *exec_path, const char *fmt, ...)
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{
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if (fmt) {
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va_list ap;
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va_start(ap, fmt);
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printf("git: ");
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vprintf(fmt, ap);
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va_end(ap);
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putchar('\n');
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}
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else
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puts(git_usage);
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putchar('\n');
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if(exec_path)
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list_commands(exec_path, "git-*");
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exit(1);
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}
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static void prepend_to_path(const char *dir, int len)
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{
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char *path, *old_path = getenv("PATH");
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int path_len = len;
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if (!old_path)
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old_path = "/usr/local/bin:/usr/bin:/bin";
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path_len = len + strlen(old_path) + 1;
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path = malloc(path_len + 1);
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memcpy(path, dir, len);
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path[len] = ':';
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memcpy(path + len + 1, old_path, path_len - len);
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setenv("PATH", path, 1);
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}
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static void show_man_page(char *git_cmd)
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{
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char *page;
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if (!strncmp(git_cmd, "git", 3))
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page = git_cmd;
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else {
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int page_len = strlen(git_cmd) + 4;
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page = malloc(page_len + 1);
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strcpy(page, "git-");
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strcpy(page + 4, git_cmd);
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page[page_len] = 0;
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}
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execlp("man", "man", page, NULL);
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}
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static int cmd_version(int argc, char **argv, char **envp)
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{
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printf("git version %s\n", GIT_VERSION);
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return 0;
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}
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static int cmd_help(int argc, char **argv, char **envp)
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{
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char *help_cmd = argv[1];
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if (!help_cmd)
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cmd_usage(git_exec_path(), NULL);
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show_man_page(help_cmd);
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return 0;
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}
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#define ARRAY_SIZE(x) (sizeof(x)/sizeof(x[0]))
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static void handle_internal_command(int argc, char **argv, char **envp)
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{
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const char *cmd = argv[0];
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static struct cmd_struct {
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const char *cmd;
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int (*fn)(int, char **, char **);
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} commands[] = {
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{ "version", cmd_version },
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{ "help", cmd_help },
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};
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int i;
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for (i = 0; i < ARRAY_SIZE(commands); i++) {
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struct cmd_struct *p = commands+i;
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if (strcmp(p->cmd, cmd))
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continue;
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exit(p->fn(argc, argv, envp));
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}
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}
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int main(int argc, char **argv, char **envp)
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{
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char *cmd = argv[0];
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char *slash = strrchr(cmd, '/');
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char git_command[PATH_MAX + 1];
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const char *exec_path = NULL;
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/*
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* Take the basename of argv[0] as the command
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* name, and the dirname as the default exec_path
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* if it's an absolute path and we don't have
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* anything better.
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*/
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if (slash) {
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*slash++ = 0;
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if (*cmd == '/')
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exec_path = cmd;
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cmd = slash;
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}
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/*
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* "git-xxxx" is the same as "git xxxx", but we obviously:
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*
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* - cannot take flags in between the "git" and the "xxxx".
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* - cannot execute it externally (since it would just do
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* the same thing over again)
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*
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* So we just directly call the internal command handler, and
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* die if that one cannot handle it.
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*/
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if (!strncmp(cmd, "git-", 4)) {
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cmd += 4;
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argv[0] = cmd;
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handle_internal_command(argc, argv, envp);
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die("cannot handle %s internally", cmd);
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}
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/* Default command: "help" */
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cmd = "help";
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/* Look for flags.. */
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while (argc > 1) {
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cmd = *++argv;
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argc--;
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if (strncmp(cmd, "--", 2))
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break;
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cmd += 2;
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/*
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* For legacy reasons, the "version" and "help"
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* commands can be written with "--" prepended
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* to make them look like flags.
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*/
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if (!strcmp(cmd, "help"))
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break;
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if (!strcmp(cmd, "version"))
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break;
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/*
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* Check remaining flags (which by now must be
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* "--exec-path", but maybe we will accept
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* other arguments some day)
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*/
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if (!strncmp(cmd, "exec-path", 9)) {
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cmd += 9;
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if (*cmd == '=') {
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git_set_exec_path(cmd + 1);
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continue;
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}
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puts(git_exec_path());
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exit(0);
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}
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cmd_usage(NULL, NULL);
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}
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argv[0] = cmd;
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/*
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* We search for git commands in the following order:
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* - git_exec_path()
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* - the path of the "git" command if we could find it
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* in $0
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* - the regular PATH.
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*/
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if (exec_path)
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prepend_to_path(exec_path, strlen(exec_path));
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exec_path = git_exec_path();
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prepend_to_path(exec_path, strlen(exec_path));
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/* See if it's an internal command */
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handle_internal_command(argc, argv, envp);
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/* .. then try the external ones */
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execv_git_cmd(argv);
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if (errno == ENOENT)
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cmd_usage(exec_path, "'%s' is not a git-command", cmd);
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fprintf(stderr, "Failed to run command '%s': %s\n",
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git_command, strerror(errno));
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return 1;
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}
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