configurator: Reimplement run using popen

Rather than using fork+pipe+system+waitpid, most of which are only
available on POSIX-like systems, use popen which is also available on
Windows (under the name _popen).

Changes since v1:
- Create fread_noeintr to avoid EINTR in fread without reading any data.
- Handle short reads from fread.  This can happen with non-conformant
  libc or if EINTR occurs after reading some data.
- Define _POSIX_C_SOURCE for popen/pclose with strict implementations
  which require it (e.g. gcc with -std=c11).

Changes since v2:
- Revert fread_noeintr and short read changes in v1 as unnecessary.

Signed-off-by: Kevin Locke <kevin@kevinlocke.name>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

diff --git a/tools/configurator/configurator.c b/tools/configurator/configurator.c
index c7577c0cb661f028585d1aac397af363a6e7cb4e..2ad3fffa254b277130ad4e34c545f91aef886f03 100644 (file)
--- a/tools/configurator/configurator.c
+++ b/tools/configurator/configurator.c
@@ -21,17 +21,19 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  * THE SOFTWARE.
  */
+#define _POSIX_C_SOURCE 200809L                /* For pclose, popen, strdup */
+
 #include <stdio.h>
 #include <stdbool.h>
 #include <stdlib.h>
-#include <unistd.h>
 #include <err.h>
-#include <sys/types.h>
-#include <sys/wait.h>
-#include <sys/stat.h>
-#include <fcntl.h>
 #include <string.h>
 
+#ifdef _MSC_VER
+#define popen _popen
+#define pclose _pclose
+#endif
+
 #define DEFAULT_COMPILER "cc"
 #define DEFAULT_FLAGS "-g3 -ggdb -Wall -Wundef -Wmissing-prototypes -Wmissing-declarations -Wstrict-prototypes -Wold-style-definition"
 
@@ -375,20 +377,19 @@ static struct test tests[] = {
        },
 };
 
-static char *grab_fd(int fd)
+static char *grab_stream(FILE *file)
 {
-       int ret;
-       size_t max, size = 0;
+       size_t max, ret, size = 0;
        char *buffer;
 
-       max = 16384;
-       buffer = malloc(max+1);
-       while ((ret = read(fd, buffer + size, max - size)) > 0) {
+       max = BUFSIZ;
+       buffer = malloc(max);
+       while ((ret = fread(buffer+size, 1, max - size, file)) == max - size) {
                size += ret;
-               if (size == max)
-                       buffer = realloc(buffer, max *= 2);
+               buffer = realloc(buffer, max *= 2);
        }
-       if (ret < 0)
+       size += ret;
+       if (ferror(file))
                err(1, "reading from command");
        buffer[size] = '\0';
        return buffer;
@@ -396,43 +397,25 @@ static char *grab_fd(int fd)
 
 static char *run(const char *cmd, int *exitstatus)
 {
-       pid_t pid;
-       int p[2];
+       static const char redir[] = " 2>&1";
+       size_t cmdlen;
+       char *cmdredir;
+       FILE *cmdout;
        char *ret;
-       int status;
 
-       if (pipe(p) != 0)
-               err(1, "creating pipe");
-
-       pid = fork();
-       if (pid == -1)
-               err(1, "forking");
-
-       if (pid == 0) {
-               if (dup2(p[1], STDOUT_FILENO) != STDOUT_FILENO
-                   || dup2(p[1], STDERR_FILENO) != STDERR_FILENO
-                   || close(p[0]) != 0
-                   || close(STDIN_FILENO) != 0
-                   || open("/dev/null", O_RDONLY) != STDIN_FILENO)
-                       exit(128);
-
-               status = system(cmd);
-               if (WIFEXITED(status))
-                       exit(WEXITSTATUS(status));
-               /* Here's a hint... */
-               exit(128 + WTERMSIG(status));
-       }
+       cmdlen = strlen(cmd);
+       cmdredir = malloc(cmdlen + sizeof(redir));
+       memcpy(cmdredir, cmd, cmdlen);
+       memcpy(cmdredir + cmdlen, redir, sizeof(redir));
+
+       cmdout = popen(cmdredir, "r");
+       if (!cmdout)
+               err(1, "popen \"%s\"", cmdredir);
+
+       free(cmdredir);
 
-       close(p[1]);
-       ret = grab_fd(p[0]);
-       /* This shouldn't fail... */
-       if (waitpid(pid, &status, 0) != pid)
-               err(1, "Failed to wait for child");
-       close(p[0]);
-       if (WIFEXITED(status))
-               *exitstatus = WEXITSTATUS(status);
-       else
-               *exitstatus = -WTERMSIG(status);
+       ret = grab_stream(cmdout);
+       *exitstatus = pclose(cmdout);
        return ret;
 }