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authorAndreas Ericsson <exon@op5.se>2005-11-15 23:31:25 (GMT)
committerJunio C Hamano <junkio@cox.net>2005-11-16 00:02:57 (GMT)
commit8e49d50388211a0f3e7286f6ee600bf7736f4814 (patch)
treef28dc659b25e44f228ffbe560ad2040718d34050 /git.c
parentc0bbbb1ba93154e31f05eab69fee70006fe7acb2 (diff)
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C implementation of the 'git' program, take two.
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>
Diffstat (limited to 'git.c')
-rw-r--r--git.c229
1 files changed, 229 insertions, 0 deletions
diff --git a/git.c b/git.c
new file mode 100644
index 0000000..d189801
--- /dev/null
+++ b/git.c
@@ -0,0 +1,229 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <limits.h>
+#include <stdarg.h>
+#include <glob.h>
+
+#ifndef PATH_MAX
+# define PATH_MAX 4096
+#endif
+
+static const char git_usage[] =
+ "Usage: git [--version] [--exec-path[=GIT_EXEC_PATH]] [--help] COMMAND [ ARGS ]";
+
+struct string_list {
+ size_t len;
+ char *str;
+ struct string_list *next;
+};
+
+/* most gui terms set COLUMNS (although some don't export it) */
+static int term_columns(void)
+{
+ char *col_string = getenv("COLUMNS");
+ int n_cols = 0;
+
+ if (col_string && (n_cols = atoi(col_string)) > 0)
+ return n_cols;
+
+ return 80;
+}
+
+static inline void mput_char(char c, unsigned int num)
+{
+ while(num--)
+ putchar(c);
+}
+
+static void pretty_print_string_list(struct string_list *list, int longest)
+{
+ int cols = 1;
+ int space = longest + 1; /* min 1 SP between words */
+ int max_cols = term_columns() - 1; /* don't print *on* the edge */
+
+ if (space < max_cols)
+ cols = max_cols / space;
+
+ while (list) {
+ int c;
+ printf(" ");
+
+ for (c = cols; c && list; list = list->next) {
+ printf("%s", list->str);
+
+ if (--c)
+ mput_char(' ', space - list->len);
+ }
+ putchar('\n');
+ }
+}
+
+static void list_commands(const char *exec_path, const char *pattern)
+{
+ struct string_list *list = NULL, *tail = NULL;
+ unsigned int longest = 0, i;
+ glob_t gl;
+
+ if (chdir(exec_path) < 0) {
+ printf("git: '%s': %s\n", exec_path, strerror(errno));
+ exit(1);
+ }
+
+ i = glob(pattern, 0, NULL, &gl);
+ switch(i) {
+ case GLOB_NOSPACE:
+ puts("Out of memory when running glob()");
+ exit(2);
+ case GLOB_ABORTED:
+ printf("'%s': Read error: %s\n", exec_path, strerror(errno));
+ exit(2);
+ case GLOB_NOMATCH:
+ printf("No git commands available in '%s'.\n", exec_path);
+ printf("Do you need to specify --exec-path or set GIT_EXEC_PATH?\n");
+ exit(1);
+ }
+
+ for (i = 0; i < gl.gl_pathc; i++) {
+ int len = strlen(gl.gl_pathv[i] + 4);
+
+ if (access(gl.gl_pathv[i], X_OK))
+ continue;
+
+ if (longest < len)
+ longest = len;
+
+ if (!tail)
+ tail = list = malloc(sizeof(struct string_list));
+ else {
+ tail->next = malloc(sizeof(struct string_list));
+ tail = tail->next;
+ }
+ tail->len = len;
+ tail->str = gl.gl_pathv[i] + 4;
+ tail->next = NULL;
+ }
+
+ printf("git commands available in '%s'\n", exec_path);
+ printf("----------------------------");
+ mput_char('-', strlen(exec_path));
+ putchar('\n');
+ pretty_print_string_list(list, longest);
+ putchar('\n');
+}
+
+#ifdef __GNUC__
+static void usage(const char *exec_path, const char *fmt, ...)
+ __attribute__((__format__(__printf__, 2, 3), __noreturn__));
+#endif
+static void usage(const char *exec_path, const char *fmt, ...)
+{
+ if (fmt) {
+ va_list ap;
+
+ va_start(ap, fmt);
+ printf("git: ");
+ vprintf(fmt, ap);
+ va_end(ap);
+ putchar('\n');
+ }
+ else
+ puts(git_usage);
+
+ putchar('\n');
+
+ if(exec_path)
+ list_commands(exec_path, "git-*");
+
+ exit(1);
+}
+
+static void prepend_to_path(const char *dir, int len)
+{
+ char *path, *old_path = getenv("PATH");
+ int path_len = len;
+
+ if (!old_path)
+ old_path = "/bin:/usr/bin:.";
+
+ path_len = len + strlen(old_path) + 1;
+
+ path = malloc(path_len + 1);
+ path[path_len + 1] = '\0';
+
+ memcpy(path, dir, len);
+ path[len] = ':';
+ memcpy(path + len + 1, old_path, path_len - len);
+
+ setenv("PATH", path, 1);
+}
+
+int main(int argc, char **argv, char **envp)
+{
+ char git_command[PATH_MAX + 1];
+ char wd[PATH_MAX + 1];
+ int i, len, show_help = 0;
+ char *exec_path = getenv("GIT_EXEC_PATH");
+
+ getcwd(wd, PATH_MAX);
+
+ if (!exec_path)
+ exec_path = GIT_EXEC_PATH;
+
+ for (i = 1; i < argc; i++) {
+ char *arg = argv[i];
+
+ if (strncmp(arg, "--", 2))
+ break;
+
+ arg += 2;
+
+ if (!strncmp(arg, "exec-path", 9)) {
+ arg += 9;
+ if (*arg == '=')
+ exec_path = arg + 1;
+ else {
+ puts(exec_path);
+ exit(0);
+ }
+ }
+ else if (!strcmp(arg, "version")) {
+ printf("git version %s\n", GIT_VERSION);
+ exit(0);
+ }
+ else if (!strcmp(arg, "help"))
+ show_help = 1;
+ else if (!show_help)
+ usage(NULL, NULL);
+ }
+
+ if (i >= argc || show_help)
+ usage(exec_path, NULL);
+
+ /* allow relative paths, but run with exact */
+ if (chdir(exec_path)) {
+ printf("git: '%s': %s\n", exec_path, strerror(errno));
+ exit (1);
+ }
+
+ getcwd(git_command, sizeof(git_command));
+ chdir(wd);
+
+ len = strlen(git_command);
+ prepend_to_path(git_command, len);
+
+ strncat(&git_command[len], "/git-", sizeof(git_command) - len);
+ len += 5;
+ strncat(&git_command[len], argv[i], sizeof(git_command) - len);
+
+ if (access(git_command, X_OK))
+ usage(exec_path, "'%s' is not a git-command", argv[i]);
+
+ /* execve() can only ever return if it fails */
+ execve(git_command, &argv[i], envp);
+ printf("Failed to run command '%s': %s\n", git_command, strerror(errno));
+
+ return 1;
+}