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Fix UB in test_unistd_write_broken_link #23125

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Merged
dschuff merged 2 commits into from
Dec 11, 2024
Merged

Fix UB in test_unistd_write_broken_link #23125

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0cdb50f
Fix UB in test_unistd_write_broken_link
dschuff Dec 10, 2024
c712243
memset
dschuff Dec 10, 2024
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9 changes: 6 additions & 3 deletions test/unistd/test_unistd_write_broken_link.c
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Original file line number Diff line number Diff line change
@@ -1,3 +1,4 @@
#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
Expand All @@ -10,21 +11,23 @@ int main() {
printf("link result: %d\n", res);
int src_fd = open("link_source", O_CREAT | O_WRONLY, 0777);
printf("source_fd: %d, errno: %d %s\n", src_fd, errno, strerror(errno));
write(src_fd, "abc", 3);
write(src_fd, "abc\0", 4);
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@sbc100 sbc100 Dec 10, 2024

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Seems a little odd to write null byte to a text file.. but I guess its not important here.

close(src_fd);
{
int target_fd = open("link_target", O_RDONLY);
printf("target_fd: %d, errno: %d %s\n", target_fd, errno, strerror(errno));
char buf[10];
read(target_fd, buf, 10);
size_t r = read(target_fd, buf, 10);
assert(r == 4);
printf("buf: '%s'\n", buf);
close(target_fd);
}
{
int target_fd = open("link_source", O_RDONLY);
printf("target_fd: %d, errno: %d %s\n", target_fd, errno, strerror(errno));
char buf[10];
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@sbc100 sbc100 Dec 10, 2024

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An alternative here I suppose would be intialize buf on the stack with char buf[10] = { '\0' };

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@dschuff dschuff Dec 10, 2024

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Yeah, I could go either way on that, do you have a preference?

read(target_fd, buf, 10);
size_t r = read(target_fd, buf, 10);
assert(r == 4);
printf("buf: '%s'\n", buf);
close(target_fd);
}
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