git.c

   1 #include <stdio.h>
   2 #include <sys/types.h>
   3 #include <sys/stat.h>
   4 #include <dirent.h>
   5 #include <unistd.h>
   6 #include <stdlib.h>
   7 #include <string.h>
   8 #include <errno.h>
   9 #include <limits.h>
  10 #include <stdarg.h>
  11 #include <sys/ioctl.h>
  12 #include "git-compat-util.h"
  13 #include "exec_cmd.h"
  14
  15 #ifndef PATH_MAX
  16 # define PATH_MAX 4096
  17 #endif
  18
  19 static const char git_usage[] =
  20         "Usage: git [--version] [--exec-path[=GIT_EXEC_PATH]] [--help] COMMAND [ ARGS ]";
  21
  22 /* most gui terms set COLUMNS (although some don't export it) */
  23 static int term_columns(void)
  24 {
  25         char *col_string = getenv("COLUMNS");
  26         int n_cols = 0;
  27
  28         if (col_string && (n_cols = atoi(col_string)) > 0)
  29                 return n_cols;
  30
  31 #ifdef TIOCGWINSZ
  32         {
  33                 struct winsize ws;
  34                 if (!ioctl(1, TIOCGWINSZ, &ws)) {
  35                         if (ws.ws_col)
  36                                 return ws.ws_col;
  37                 }
  38         }
  39 #endif
  40
  41         return 80;
  42 }
  43
  44 static void oom(void)
  45 {
  46         fprintf(stderr, "git: out of memory\n");
  47         exit(1);
  48 }
  49
  50 static inline void mput_char(char c, unsigned int num)
  51 {
  52         while(num--)
  53                 putchar(c);
  54 }
  55
  56 static struct cmdname {
  57         size_t len;
  58         char name[1];
  59 } **cmdname;
  60 static int cmdname_alloc, cmdname_cnt;
  61
  62 static void add_cmdname(const char *name, int len)
  63 {
  64         struct cmdname *ent;
  65         if (cmdname_alloc <= cmdname_cnt) {
  66                 cmdname_alloc = cmdname_alloc + 200;
  67                 cmdname = realloc(cmdname, cmdname_alloc * sizeof(*cmdname));
  68                 if (!cmdname)
  69                         oom();
  70         }
  71         ent = malloc(sizeof(*ent) + len);
  72         if (!ent)
  73                 oom();
  74         ent->len = len;
  75         memcpy(ent->name, name, len);
  76         ent->name[len] = 0;
  77         cmdname[cmdname_cnt++] = ent;
  78 }
  79
  80 static int cmdname_compare(const void *a_, const void *b_)
  81 {
  82         struct cmdname *a = *(struct cmdname **)a_;
  83         struct cmdname *b = *(struct cmdname **)b_;
  84         return strcmp(a->name, b->name);
  85 }
  86
  87 static void pretty_print_string_list(struct cmdname **cmdname, int longest)
  88 {
  89         int cols = 1, rows;
  90         int space = longest + 1; /* min 1 SP between words */
  91         int max_cols = term_columns() - 1; /* don't print *on* the edge */
  92         int i, j;
  93
  94         if (space < max_cols)
  95                 cols = max_cols / space;
  96         rows = (cmdname_cnt + cols - 1) / cols;
  97
  98         qsort(cmdname, cmdname_cnt, sizeof(*cmdname), cmdname_compare);
  99
 100         for (i = 0; i < rows; i++) {
 101                 printf("  ");
 102
 103                 for (j = 0; j < cols; j++) {
 104                         int n = j * rows + i;
 105                         int size = space;
 106                         if (n >= cmdname_cnt)
 107                                 break;
 108                         if (j == cols-1 || n + rows >= cmdname_cnt)
 109                                 size = 1;
 110                         printf("%-*s", size, cmdname[n]->name);
 111                 }
 112                 putchar('\n');
 113         }
 114 }
 115
 116 static void list_commands(const char *exec_path, const char *pattern)
 117 {
 118         unsigned int longest = 0;
 119         char path[PATH_MAX];
 120         int dirlen;
 121         DIR *dir = opendir(exec_path);
 122         struct dirent *de;
 123
 124         if (!dir) {
 125                 fprintf(stderr, "git: '%s': %s\n", exec_path, strerror(errno));
 126                 exit(1);
 127         }
 128
 129         dirlen = strlen(exec_path);
 130         if (PATH_MAX - 20 < dirlen) {
 131                 fprintf(stderr, "git: insanely long exec-path '%s'\n",
 132                         exec_path);
 133                 exit(1);
 134         }
 135
 136         memcpy(path, exec_path, dirlen);
 137         path[dirlen++] = '/';
 138
 139         while ((de = readdir(dir)) != NULL) {
 140                 struct stat st;
 141                 int entlen;
 142
 143                 if (strncmp(de->d_name, "git-", 4))
 144                         continue;
 145                 strcpy(path+dirlen, de->d_name);
 146                 if (stat(path, &st) || /* stat, not lstat */
 147                     !S_ISREG(st.st_mode) ||
 148                     !(st.st_mode & S_IXUSR))
 149                         continue;
 150
 151                 entlen = strlen(de->d_name);
 152                 if (4 < entlen && !strcmp(de->d_name + entlen - 4, ".exe"))
 153                         entlen -= 4;
 154
 155                 if (longest < entlen)
 156                         longest = entlen;
 157
 158                 add_cmdname(de->d_name + 4, entlen-4);
 159         }
 160         closedir(dir);
 161
 162         printf("git commands available in '%s'\n", exec_path);
 163         printf("----------------------------");
 164         mput_char('-', strlen(exec_path));
 165         putchar('\n');
 166         pretty_print_string_list(cmdname, longest - 4);
 167         putchar('\n');
 168 }
 169
 170 #ifdef __GNUC__
 171 static void cmd_usage(const char *exec_path, const char *fmt, ...)
 172         __attribute__((__format__(__printf__, 2, 3), __noreturn__));
 173 #endif
 174 static void cmd_usage(const char *exec_path, const char *fmt, ...)
 175 {
 176         if (fmt) {
 177                 va_list ap;
 178
 179                 va_start(ap, fmt);
 180                 printf("git: ");
 181                 vprintf(fmt, ap);
 182                 va_end(ap);
 183                 putchar('\n');
 184         }
 185         else
 186                 puts(git_usage);
 187
 188         putchar('\n');
 189
 190         if(exec_path)
 191                 list_commands(exec_path, "git-*");
 192
 193         exit(1);
 194 }
 195
 196 static void prepend_to_path(const char *dir, int len)
 197 {
 198         char *path, *old_path = getenv("PATH");
 199         int path_len = len;
 200
 201         if (!old_path)
 202                 old_path = "/usr/local/bin:/usr/bin:/bin";
 203
 204         path_len = len + strlen(old_path) + 1;
 205
 206         path = malloc(path_len + 1);
 207
 208         memcpy(path, dir, len);
 209         path[len] = ':';
 210         memcpy(path + len + 1, old_path, path_len - len);
 211
 212         setenv("PATH", path, 1);
 213 }
 214
 215 static void show_man_page(char *git_cmd)
 216 {
 217         char *page;
 218
 219         if (!strncmp(git_cmd, "git", 3))
 220                 page = git_cmd;
 221         else {
 222                 int page_len = strlen(git_cmd) + 4;
 223
 224                 page = malloc(page_len + 1);
 225                 strcpy(page, "git-");
 226                 strcpy(page + 4, git_cmd);
 227                 page[page_len] = 0;
 228         }
 229
 230         execlp("man", "man", page, NULL);
 231 }
 232
 233 static int cmd_version(int argc, char **argv, char **envp)
 234 {
 235         printf("git version %s\n", GIT_VERSION);
 236         return 0;
 237 }
 238
 239 static int cmd_help(int argc, char **argv, char **envp)
 240 {
 241         char *help_cmd = argv[1];
 242         if (!help_cmd)
 243                 cmd_usage(git_exec_path(), NULL);
 244         show_man_page(help_cmd);
 245         return 0;
 246 }
 247
 248 #define ARRAY_SIZE(x) (sizeof(x)/sizeof(x[0]))
 249
 250 static void handle_internal_command(int argc, char **argv, char **envp)
 251 {
 252         const char *cmd = argv[0];
 253         static struct cmd_struct {
 254                 const char *cmd;
 255                 int (*fn)(int, char **, char **);
 256         } commands[] = {
 257                 { "version", cmd_version },
 258                 { "help", cmd_help },
 259         };
 260         int i;
 261
 262         for (i = 0; i < ARRAY_SIZE(commands); i++) {
 263                 struct cmd_struct *p = commands+i;
 264                 if (strcmp(p->cmd, cmd))
 265                         continue;
 266                 exit(p->fn(argc, argv, envp));
 267         }
 268 }
 269
 270 int main(int argc, char **argv, char **envp)
 271 {
 272         char *cmd = argv[0];
 273         char *slash = strrchr(cmd, '/');
 274         char git_command[PATH_MAX + 1];
 275         const char *exec_path = NULL;
 276
 277         /*
 278          * Take the basename of argv[0] as the command
 279          * name, and the dirname as the default exec_path
 280          * if it's an absolute path and we don't have
 281          * anything better.
 282          */
 283         if (slash) {
 284                 *slash++ = 0;
 285                 if (*cmd == '/')
 286                         exec_path = cmd;
 287                 cmd = slash;
 288         }
 289
 290         /*
 291          * "git-xxxx" is the same as "git xxxx", but we obviously:
 292          *
 293          *  - cannot take flags in between the "git" and the "xxxx".
 294          *  - cannot execute it externally (since it would just do
 295          *    the same thing over again)
 296          *
 297          * So we just directly call the internal command handler, and
 298          * die if that one cannot handle it.
 299          */
 300         if (!strncmp(cmd, "git-", 4)) {
 301                 cmd += 4;
 302                 argv[0] = cmd;
 303                 handle_internal_command(argc, argv, envp);
 304                 die("cannot handle %s internally", cmd);
 305         }
 306
 307         /* Default command: "help" */
 308         cmd = "help";
 309
 310         /* Look for flags.. */
 311         while (argc > 1) {
 312                 cmd = *++argv;
 313                 argc--;
 314
 315                 if (strncmp(cmd, "--", 2))
 316                         break;
 317
 318                 cmd += 2;
 319
 320                 /*
 321                  * For legacy reasons, the "version" and "help"
 322                  * commands can be written with "--" prepended
 323                  * to make them look like flags.
 324                  */
 325                 if (!strcmp(cmd, "help"))
 326                         break;
 327                 if (!strcmp(cmd, "version"))
 328                         break;
 329
 330                 /*
 331                  * Check remaining flags (which by now must be
 332                  * "--exec-path", but maybe we will accept
 333                  * other arguments some day)
 334                  */
 335                 if (!strncmp(cmd, "exec-path", 9)) {
 336                         cmd += 9;
 337                         if (*cmd == '=') {
 338                                 git_set_exec_path(cmd + 1);
 339                                 continue;
 340                         }
 341                         puts(git_exec_path());
 342                         exit(0);
 343                 }
 344                 cmd_usage(NULL, NULL);
 345         }
 346         argv[0] = cmd;
 347
 348         /*
 349          * We search for git commands in the following order:
 350          *  - git_exec_path()
 351          *  - the path of the "git" command if we could find it
 352          *    in $0
 353          *  - the regular PATH.
 354          */
 355         if (exec_path)
 356                 prepend_to_path(exec_path, strlen(exec_path));
 357         exec_path = git_exec_path();
 358         prepend_to_path(exec_path, strlen(exec_path));
 359
 360         /* See if it's an internal command */
 361         handle_internal_command(argc, argv, envp);
 362
 363         /* .. then try the external ones */
 364         execv_git_cmd(argv);
 365
 366         if (errno == ENOENT)
 367                 cmd_usage(exec_path, "'%s' is not a git-command", cmd);
 368
 369         fprintf(stderr, "Failed to run command '%s': %s\n",
 370                 git_command, strerror(errno));
 371
 372         return 1;
 373 }