On Sun, Sep 18, 2016 at 06:51:59PM -0600, Kevin Locke wrote: > 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).
Concept looks good, one little wart.
>
> Signed-off-by: Kevin Locke <ke...@kevinlocke.name>
> ---
> tools/configurator/configurator.c | 77
> +++++++++++++++------------------------
> 1 file changed, 29 insertions(+), 48 deletions(-)
>
> diff --git a/tools/configurator/configurator.c
> b/tools/configurator/configurator.c
> index e322c76..9817fcd 100644
> --- a/tools/configurator/configurator.c
> +++ b/tools/configurator/configurator.c
> @@ -24,14 +24,14 @@
> #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"
>
> @@ -367,20 +367,19 @@ 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) {
This assumes that fread() will never return a short read except on EOF
or error. I expect that will be true in practice for regular files,
but I'm not sure if it's a good idea to rely on it.
> 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;
> @@ -388,43 +387,25 @@ 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;
> }
>
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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