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https://github.com/git/git
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![Andreas Ericsson](/assets/img/avatar_default.png)
This patch provides a C implementation of the 'git' program and introduces support for putting the git-* commands in a directory of their own. It also saves some time on executing those commands in a tight loop and it prints the currently available git commands in a nicely formatted list. The location of the GIT_EXEC_PATH (name discussion's closed, thank gods) can be obtained by running git --exec-path which will hopefully give porcelainistas ample time to adapt their heavy-duty loops to call the core programs directly and thus save the extra fork() / execve() overhead, although that's not really necessary any more. The --exec-path value is prepended to $PATH, so the git-* programs should Just Work without ever requiring any changes to how they call other programs in the suite. Some timing values for 10000 invocations of git-var >&/dev/null: git.sh: 24.194s git.c: 9.044s git-var: 7.377s The git-<tab><tab> behaviour can, along with the someday-to-be-deprecated git-<command> form of invocation, be indefinitely retained by adding the following line to one's .bash_profile or equivalent: PATH=$PATH:$(git --exec-path) Experimental libraries can be used by either setting the environment variable GIT_EXEC_PATH, or by using git --exec-path=/some/experimental/exec-path Relative paths are properly grok'ed as exec-path values. Signed-off-by: Andreas Ericsson <ae@op5.se> Signed-off-by: Junio C Hamano <junkio@cox.net>
230 lines
4.6 KiB
C
230 lines
4.6 KiB
C
#include <stdio.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 <glob.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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struct string_list {
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size_t len;
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char *str;
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struct string_list *next;
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};
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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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return 80;
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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 void pretty_print_string_list(struct string_list *list, int longest)
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{
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int cols = 1;
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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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if (space < max_cols)
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cols = max_cols / space;
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while (list) {
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int c;
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printf(" ");
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for (c = cols; c && list; list = list->next) {
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printf("%s", list->str);
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if (--c)
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mput_char(' ', space - list->len);
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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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struct string_list *list = NULL, *tail = NULL;
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unsigned int longest = 0, i;
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glob_t gl;
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if (chdir(exec_path) < 0) {
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printf("git: '%s': %s\n", exec_path, strerror(errno));
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exit(1);
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}
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i = glob(pattern, 0, NULL, &gl);
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switch(i) {
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case GLOB_NOSPACE:
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puts("Out of memory when running glob()");
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exit(2);
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case GLOB_ABORTED:
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printf("'%s': Read error: %s\n", exec_path, strerror(errno));
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exit(2);
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case GLOB_NOMATCH:
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printf("No git commands available in '%s'.\n", exec_path);
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printf("Do you need to specify --exec-path or set GIT_EXEC_PATH?\n");
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exit(1);
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}
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for (i = 0; i < gl.gl_pathc; i++) {
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int len = strlen(gl.gl_pathv[i] + 4);
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if (access(gl.gl_pathv[i], X_OK))
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continue;
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if (longest < len)
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longest = len;
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if (!tail)
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tail = list = malloc(sizeof(struct string_list));
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else {
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tail->next = malloc(sizeof(struct string_list));
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tail = tail->next;
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}
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tail->len = len;
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tail->str = gl.gl_pathv[i] + 4;
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tail->next = NULL;
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}
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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(list, longest);
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putchar('\n');
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}
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#ifdef __GNUC__
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static void 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 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 = "/bin:/usr/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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path[path_len + 1] = '\0';
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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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int main(int argc, char **argv, char **envp)
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{
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char git_command[PATH_MAX + 1];
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char wd[PATH_MAX + 1];
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int i, len, show_help = 0;
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char *exec_path = getenv("GIT_EXEC_PATH");
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getcwd(wd, PATH_MAX);
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if (!exec_path)
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exec_path = GIT_EXEC_PATH;
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for (i = 1; i < argc; i++) {
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char *arg = argv[i];
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if (strncmp(arg, "--", 2))
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break;
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arg += 2;
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if (!strncmp(arg, "exec-path", 9)) {
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arg += 9;
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if (*arg == '=')
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exec_path = arg + 1;
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else {
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puts(exec_path);
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exit(0);
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}
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}
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else if (!strcmp(arg, "version")) {
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printf("git version %s\n", GIT_VERSION);
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exit(0);
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}
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else if (!strcmp(arg, "help"))
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show_help = 1;
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else if (!show_help)
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usage(NULL, NULL);
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}
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if (i >= argc || show_help)
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usage(exec_path, NULL);
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/* allow relative paths, but run with exact */
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if (chdir(exec_path)) {
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printf("git: '%s': %s\n", exec_path, strerror(errno));
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exit (1);
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}
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getcwd(git_command, sizeof(git_command));
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chdir(wd);
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len = strlen(git_command);
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prepend_to_path(git_command, len);
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strncat(&git_command[len], "/git-", sizeof(git_command) - len);
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len += 5;
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strncat(&git_command[len], argv[i], sizeof(git_command) - len);
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if (access(git_command, X_OK))
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usage(exec_path, "'%s' is not a git-command", argv[i]);
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/* execve() can only ever return if it fails */
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execve(git_command, &argv[i], envp);
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printf("Failed to run command '%s': %s\n", git_command, strerror(errno));
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return 1;
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}
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