spawn-pipe.c

   1 #include "git-compat-util.h"
   2 #include "spawn-pipe.h"
   3
   4 extern char **environ;
   5
   6 #ifdef __MINGW32__
   7 static char *lookup_prog(const char *dir, const char *cmd, int tryexe)
   8 {
   9         char path[MAX_PATH];
  10         snprintf(path, sizeof(path), "%s/%s.exe", dir, cmd);
  11
  12         if (tryexe && access(path, 0) == 0)
  13                 return xstrdup(path);
  14         path[strlen(path)-4] = '\0';
  15         if (access(path, 0) == 0)
  16                 return xstrdup(path);
  17         return NULL;
  18 }
  19
  20 /*
  21  * Splits the PATH into parts.
  22  */
  23 char **get_path_split()
  24 {
  25         char *p, **path, *envpath = getenv("PATH");
  26         int i, n = 0;
  27
  28         if (!envpath || !*envpath)
  29                 return NULL;
  30
  31         envpath = xstrdup(envpath);
  32         p = envpath;
  33         while (p) {
  34                 char *dir = p;
  35                 p = strchr(p, ';');
  36                 if (p) *p++ = '\0';
  37                 if (*dir) {     /* not earlier, catches series of ; */
  38                         ++n;
  39                 }
  40         }
  41         if (!n)
  42                 return NULL;
  43
  44         path = xmalloc((n+1)*sizeof(char*));
  45         p = envpath;
  46         i = 0;
  47         do {
  48                 if (*p)
  49                         path[i++] = xstrdup(p);
  50                 p = p+strlen(p)+1;
  51         } while (i < n);
  52         path[i] = NULL;
  53
  54         free(envpath);
  55
  56         return path;
  57 }
  58
  59 void free_path_split(char **path)
  60 {
  61         if (!path)
  62                 return;
  63
  64         char **p = path;
  65         while (*p)
  66                 free(*p++);
  67         free(path);
  68 }
  69
  70 /*
  71  * Determines the absolute path of cmd using the the split path in path.
  72  * If cmd contains a slash or backslash, no lookup is performed.
  73  */
  74 static char *path_lookup(const char *cmd, char **path)
  75 {
  76         char **p = path;
  77         char *prog = NULL;
  78         int len = strlen(cmd);
  79         int tryexe = len < 4 || strcasecmp(cmd+len-4, ".exe");
  80
  81         if (strchr(cmd, '/') || strchr(cmd, '\\'))
  82                 prog = xstrdup(cmd);
  83
  84         while (!prog && *p) {
  85                 prog = lookup_prog(*p++, cmd, tryexe);
  86         }
  87         if (!prog) {
  88                 prog = lookup_prog(".", cmd, tryexe);
  89                 if (!prog)
  90                         prog = xstrdup(cmd);
  91         }
  92         return prog;
  93 }
  94 #endif
  95
  96 /* cmd specifies the command to invoke.
  97  * argv specifies its arguments; argv[0] will be replaced by the basename of cmd.
  98  * env specifies the environment.
  99  * pin and pout specify pipes; the read end of pin is made the standard input
 100  * of the spawned process, and the write end of pout is mad the standard output.
 101  * The respective unused ends of the pipes are closed both in the parent
 102  * process as well as in the child process.
 103  * Anyone of pin or pout can be NULL, or any one of the ends can be -1 to
 104  * indicate that no processing shall occur.
 105  */
 106 int spawnvpe_pipe(const char *cmd, const char **argv, const char **env,
 107                   int pin[], int pout[])
 108 {
 109         char **path = get_path_split();
 110
 111         pid_t pid = spawnvppe_pipe(cmd, argv, env, path, pin, pout);
 112
 113         free_path_split(path);
 114
 115         return pid;
 116 }
 117
 118 int spawnvppe_pipe(const char *cmd, const char **argv, const char **env,
 119                   char **path,
 120                   int pin[], int pout[])
 121 {
 122         const char *cmd_basename = strrchr(cmd, '/');
 123         pid_t pid;
 124
 125 #ifdef __MINGW32__
 126         int s0 = -1, s1 = -1, argc;
 127         char *prog;
 128         const char **qargv, *interpr;
 129
 130         if (!cmd_basename)
 131                 cmd_basename = strrchr(cmd, '\\');
 132 #endif
 133
 134         if (!cmd_basename)
 135                 cmd_basename = cmd;
 136         else
 137                 cmd_basename++;
 138         argv[0] = cmd_basename;
 139
 140 #ifndef __MINGW32__
 141         pid = fork();
 142         if (pid < 0)
 143                 die("unable to fork");
 144         if (!pid) {
 145                 if (pin) {
 146                         if (pin[0] >= 0) {
 147                                 dup2(pin[0], 0);
 148                                 close(pin[0]);
 149                         }
 150                         if (pin[1] >= 0)
 151                                 close(pin[1]);
 152                 }
 153                 if (pout) {
 154                         if (pout[1] >= 0) {
 155                                 dup2(pout[1], 1);
 156                                 close(pout[1]);
 157                         }
 158                         if (pout[0] >= 0)
 159                                 close(pout[0]);
 160                 }
 161                 environ = env;
 162                 execvp(cmd, argv);
 163                 die("exec failed");
 164         }
 165
 166         if (pin && pin[0] >= 0)
 167                 close(pin[0]);
 168         if (pout && pout[1] >= 1)
 169                 close(pout[1]);
 170 #else
 171         if (pin) {
 172                 if (pin[0] >= 0) {
 173                         s0 = dup(0);
 174                         dup2(pin[0], 0);
 175                         close(pin[0]);
 176                 }
 177         }
 178         if (pout) {
 179                 if (pout[1] >= 0) {
 180                         s1 = dup(1);
 181                         dup2(pout[1], 1);
 182                         close(pout[1]);
 183                 }
 184         }
 185
 186         prog = path_lookup(cmd, path);
 187         interpr = parse_interpreter(prog);
 188
 189         for (argc = 0; argv[argc];) argc++;
 190         qargv = xmalloc((argc+2)*sizeof(char*));
 191         if (!interpr) {
 192                 quote_argv(qargv, argv);
 193                 pid = spawnve(_P_NOWAIT, prog, qargv, env);
 194         } else {
 195                 qargv[0] = interpr;
 196                 argv[0] = prog;
 197                 quote_argv(&qargv[1], argv);
 198                 pid = spawnvpe(_P_NOWAIT, interpr, qargv, env);
 199         }
 200
 201         free(qargv);            /* TODO: quoted args should be freed, too */
 202         free(prog);
 203
 204         if (s0 >= 0) {
 205                 dup2(s0, 0);
 206                 close(s0);
 207         }
 208         if (s1 >= 0) {
 209                 dup2(s1, 1);
 210                 close(s1);
 211         }
 212 #endif
 213
 214         return pid;
 215 }
 216
 217 const char **copy_environ()
 218 {
 219         return copy_env(environ);
 220 }
 221
 222 const char **copy_env(const char **env)
 223 {
 224         const char **s;
 225         int n = 1;
 226         for (s = env; *s; s++)
 227                 n++;
 228         s = xmalloc(n*sizeof(const char *));
 229         memcpy(s, env, n*sizeof(const char *));
 230         return s;
 231 }
 232
 233 void env_unsetenv(const char **env, const char *name)
 234 {
 235         int src, dst;
 236         size_t nmln;
 237
 238         nmln = strlen(name);
 239
 240         for (src = dst = 0; env[src]; ++src) {
 241                 size_t enln;
 242                 enln = strlen(env[src]);
 243                 if (enln > nmln) {
 244                         /* might match, and can test for '=' safely */
 245                         if (0 == strncmp (env[src], name, nmln)
 246                             && '=' == env[src][nmln])
 247                                 /* matches, so skip */
 248                                 continue;
 249                 }
 250                 env[dst] = env[src];
 251                 ++dst;
 252         }
 253         env[dst] = NULL;
 254 }