avoid malloc of potentially-large string in wordexp

diff --git a/src/misc/wordexp.c b/src/misc/wordexp.c
index 01217ab..171f270 100644 (file)
--- a/src/misc/wordexp.c
+++ b/src/misc/wordexp.c
@@ -5,6 +5,8 @@
 #include <limits.h>
 #include <stdint.h>
 #include <stdlib.h>
+#include <sys/wait.h>
+#include <signal.h>
 
 static char *getword(FILE *f)
 {
@@ -14,15 +16,17 @@ static char *getword(FILE *f)
 
 int wordexp(const char *s, wordexp_t *we, int flags)
 {
-       size_t i, l, len;
+       size_t i, l;
        int sq=0, dq=0;
        size_t np=0;
-       char *cmd, *w, **tmp;
+       char *w, **tmp;
        char *redir = (flags & WRDE_SHOWERR) ? "" : "2>/dev/null";
        int err = 0, status;
        FILE *f;
        size_t wc = 0;
        char **wv = 0;
+       int p[2];
+       pid_t pid;
 
        if (flags & WRDE_REUSE) wordfree(we);
 
@@ -79,13 +83,26 @@ int wordexp(const char *s, wordexp_t *we, int flags)
                i += we->we_offs;
        }
 
-       len = 50 + strlen(s);
-       cmd = malloc(len);
-       if (!cmd) return WRDE_NOSPACE;
-       snprintf(cmd, len, "printf %%s\\\\0 %s %s", s, redir);
-       f = popen(cmd, "r");
-       free(cmd);
-       if (!f) return WRDE_NOSPACE;
+       pipe(p);
+       pid = fork();
+       if (!pid) {
+               dup2(p[1], 1);
+               close(p[0]);
+               close(p[1]);
+               execl("/bin/sh", "sh", "-c",
+                       "eval \"printf %s\\\\\\\\0 $1 $2\"",
+                       "sh", s, redir, (char *)0);
+               _exit(1);
+       }
+       close(p[1]);
+       
+       f = fdopen(p[0], "r");
+       if (!f) {
+               close(p[0]);
+               kill(pid, SIGKILL);
+               waitpid(pid, &status, 0);
+               return WRDE_NOSPACE;
+       }
 
        l = wv ? i+1 : 0;
 
@@ -101,7 +118,8 @@ int wordexp(const char *s, wordexp_t *we, int flags)
        }
        if (!feof(f)) err = WRDE_NOSPACE;
 
-       status = pclose(f);
+       fclose(f);
+       waitpid(pid, &status, 0);
        if (WEXITSTATUS(status)) {
                if (!(flags & WRDE_APPEND)) {
                        free(wv);