I don't think the #ifdef is necessary, EINTR if defined in POSIX and POSIX specifies that EINTR can be returned by read(3). Additionally, checking if EINTR is defined would be better.
However, there is no need to check for EINTR unless the program
catches signals. Is there any tools in sbase that both use concat
and catch signals?
On Sun, 23 Jul 2017 10:13:50 +0100
Richard Ipsum <richardip...@fastmail.co.uk> wrote:
> On Linux we may receive EINTR if the read call is interrupted
> before any data is read, if this is the case we can try to read
> again.
> ---
> libutil/concat.c | 22 +++++++++++++++++-----
> 1 file changed, 17 insertions(+), 5 deletions(-)
>
> diff --git a/libutil/concat.c b/libutil/concat.c
> index 2e9aa52..5cbadd2 100644
> --- a/libutil/concat.c
> +++ b/libutil/concat.c
> @@ -1,4 +1,5 @@
> /* See LICENSE file for copyright and license details. */
> +#include <errno.h>
> #include <unistd.h>
>
> #include "../util.h"
> @@ -9,15 +10,26 @@ concat(int f1, const char *s1, int f2, const char *s2)
> char buf[BUFSIZ];
> ssize_t n;
>
> - while ((n = read(f1, buf, sizeof(buf))) > 0) {
> + for (;;) {
> + n = read(f1, buf, sizeof(buf));
> +
> + if (n == 0)
> + break;
> +
> + if (n < 0) {
> +#ifdef __linux__
> + if (errno == EINTR)
> + continue;
> +#endif
> + weprintf("read %s:", s1);
> + return -1;
> + }
> +
> if (writeall(f2, buf, n) < 0) {
> weprintf("write %s:", s2);
> return -2;
> }
> }
> - if (n < 0) {
> - weprintf("read %s:", s1);
> - return -1;
> - }
> +
> return 0;
> }
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