git/git.c
Michal Ostrowski 77cb17e940 Exec git programs without using PATH.
The git suite may not be in PATH (and thus programs such as
git-send-pack could not exec git-rev-list).  Thus there is a need for
logic that will locate these programs.  Modifying PATH is not
desirable as it result in behavior differing from the user's
intentions, as we may end up prepending "/usr/bin" to PATH.

- git C programs will use exec*_git_cmd() APIs to exec sub-commands.
- exec*_git_cmd() will execute a git program by searching for it in
  the following directories:
	1. --exec-path (as used by "git")
	2. The GIT_EXEC_PATH environment variable.
	3. $(gitexecdir) as set in Makefile (default value $(bindir)).
- git wrapper will modify PATH as before to enable shell scripts to
  invoke "git-foo" commands.

Ideally, shell scripts should use the git wrapper to become independent
of PATH, and then modifying PATH will not be necessary.

[jc: with minor updates after a brief review.]

Signed-off-by: Michal Ostrowski <mostrows@watson.ibm.com>
Signed-off-by: Junio C Hamano <junkio@cox.net>
2006-01-13 16:49:01 -08:00

295 lines
5.7 KiB
C

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <dirent.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <limits.h>
#include <stdarg.h>
#include <sys/ioctl.h>
#include "git-compat-util.h"
#include "exec_cmd.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 ]";
/* 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;
#ifdef TIOCGWINSZ
{
struct winsize ws;
if (!ioctl(1, TIOCGWINSZ, &ws)) {
if (ws.ws_col)
return ws.ws_col;
}
}
#endif
return 80;
}
static void oom(void)
{
fprintf(stderr, "git: out of memory\n");
exit(1);
}
static inline void mput_char(char c, unsigned int num)
{
while(num--)
putchar(c);
}
static struct cmdname {
size_t len;
char name[1];
} **cmdname;
static int cmdname_alloc, cmdname_cnt;
static void add_cmdname(const char *name, int len)
{
struct cmdname *ent;
if (cmdname_alloc <= cmdname_cnt) {
cmdname_alloc = cmdname_alloc + 200;
cmdname = realloc(cmdname, cmdname_alloc * sizeof(*cmdname));
if (!cmdname)
oom();
}
ent = malloc(sizeof(*ent) + len);
if (!ent)
oom();
ent->len = len;
memcpy(ent->name, name, len);
ent->name[len] = 0;
cmdname[cmdname_cnt++] = ent;
}
static int cmdname_compare(const void *a_, const void *b_)
{
struct cmdname *a = *(struct cmdname **)a_;
struct cmdname *b = *(struct cmdname **)b_;
return strcmp(a->name, b->name);
}
static void pretty_print_string_list(struct cmdname **cmdname, int longest)
{
int cols = 1, rows;
int space = longest + 1; /* min 1 SP between words */
int max_cols = term_columns() - 1; /* don't print *on* the edge */
int i, j;
if (space < max_cols)
cols = max_cols / space;
rows = (cmdname_cnt + cols - 1) / cols;
qsort(cmdname, cmdname_cnt, sizeof(*cmdname), cmdname_compare);
for (i = 0; i < rows; i++) {
printf(" ");
for (j = 0; j < cols; j++) {
int n = j * rows + i;
int size = space;
if (n >= cmdname_cnt)
break;
if (j == cols-1 || n + rows >= cmdname_cnt)
size = 1;
printf("%-*s", size, cmdname[n]->name);
}
putchar('\n');
}
}
static void list_commands(const char *exec_path, const char *pattern)
{
unsigned int longest = 0;
char path[PATH_MAX];
int dirlen;
DIR *dir = opendir(exec_path);
struct dirent *de;
if (!dir) {
fprintf(stderr, "git: '%s': %s\n", exec_path, strerror(errno));
exit(1);
}
dirlen = strlen(exec_path);
if (PATH_MAX - 20 < dirlen) {
fprintf(stderr, "git: insanely long exec-path '%s'\n",
exec_path);
exit(1);
}
memcpy(path, exec_path, dirlen);
path[dirlen++] = '/';
while ((de = readdir(dir)) != NULL) {
struct stat st;
int entlen;
if (strncmp(de->d_name, "git-", 4))
continue;
strcpy(path+dirlen, de->d_name);
if (stat(path, &st) || /* stat, not lstat */
!S_ISREG(st.st_mode) ||
!(st.st_mode & S_IXUSR))
continue;
entlen = strlen(de->d_name);
if (4 < entlen && !strcmp(de->d_name + entlen - 4, ".exe"))
entlen -= 4;
if (longest < entlen)
longest = entlen;
add_cmdname(de->d_name + 4, entlen-4);
}
closedir(dir);
printf("git commands available in '%s'\n", exec_path);
printf("----------------------------");
mput_char('-', strlen(exec_path));
putchar('\n');
pretty_print_string_list(cmdname, longest - 4);
putchar('\n');
}
#ifdef __GNUC__
static void cmd_usage(const char *exec_path, const char *fmt, ...)
__attribute__((__format__(__printf__, 2, 3), __noreturn__));
#endif
static void cmd_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 = "/usr/local/bin:/usr/bin:/bin";
path_len = len + strlen(old_path) + 1;
path = malloc(path_len + 1);
memcpy(path, dir, len);
path[len] = ':';
memcpy(path + len + 1, old_path, path_len - len);
setenv("PATH", path, 1);
}
static void show_man_page(char *git_cmd)
{
char *page;
if (!strncmp(git_cmd, "git", 3))
page = git_cmd;
else {
int page_len = strlen(git_cmd) + 4;
page = malloc(page_len + 1);
strcpy(page, "git-");
strcpy(page + 4, git_cmd);
page[page_len] = 0;
}
execlp("man", "man", page, NULL);
}
int main(int argc, char **argv, char **envp)
{
char git_command[PATH_MAX + 1];
char wd[PATH_MAX + 1];
int i, show_help = 0;
const char *exec_path;
getcwd(wd, PATH_MAX);
for (i = 1; i < argc; i++) {
char *arg = argv[i];
if (!strcmp(arg, "help")) {
show_help = 1;
continue;
}
if (strncmp(arg, "--", 2))
break;
arg += 2;
if (!strncmp(arg, "exec-path", 9)) {
arg += 9;
if (*arg == '=') {
exec_path = arg + 1;
git_set_exec_path(exec_path);
} else {
puts(git_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)
cmd_usage(NULL, NULL);
}
if (i >= argc || show_help) {
if (i >= argc)
cmd_usage(git_exec_path(), NULL);
show_man_page(argv[i]);
}
exec_path = git_exec_path();
prepend_to_path(exec_path, strlen(exec_path));
execv_git_cmd(argv + i);
if (errno == ENOENT)
cmd_usage(exec_path, "'%s' is not a git-command", argv[i]);
fprintf(stderr, "Failed to run command '%s': %s\n",
git_command, strerror(errno));
return 1;
}