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echo: do not assume that free() leaves errno unmodified

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musl libc's mallocng free() may modify errno if kernel does not support
MADV_FREE which causes echo to echo with error when it shouldn't.

Future versions of POSIX[1] will require that free() leaves errno
unmodified but til then, do not rely free() implementation.

Should fix downstream issues:
https://github.com/alpinelinux/docker-alpine/issues/134
https://gitlab.alpinelinux.org/alpine/aports/-/issues/12311

Signed-off-by: Natanael Copa <ncopa@alpinelinux.org>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Natanael Copa 2021-01-22 08:35:55 +01:00 committed by Denys Vlasenko
parent 760b627e2a
commit e880c9c100
1 changed files with 5 additions and 5 deletions
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10
coreutils/echo.c
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@ -97,6 +97,7 @@ int echo_main(int argc UNUSED_PARAM, char **argv)
#else
char nflag = 1;
char eflag = 0;
int err;
while ((arg = *++argv) != NULL) {
char n, e;
@ -185,13 +186,12 @@ int echo_main(int argc UNUSED_PARAM, char **argv)
do_write:
/* Careful to error out on partial writes too (think ENOSPC!) */
errno = 0;
/*r =*/ full_write(STDOUT_FILENO, buffer, out - buffer);
free(buffer);
if (/*WRONG:r < 0*/ errno) {
err = full_write(STDOUT_FILENO, buffer, out - buffer) != out - buffer;
if (err) {
bb_simple_perror_msg(bb_msg_write_error);
return 1;
}
return 0;
free(buffer);
return err;
}
/*