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util: minor cleanups for loop_read() and friends

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When 0 bytes are to be written, make sure to go into read() at least
once, in order to validate the parameters, such as the passed fd.

Return error on huge values, add a couple of asserts and casts where
appropriate.
This commit is contained in:
Lennart Poettering 2015-09-19 00:47:08 +02:00
parent 1fc464f6fb
commit 4fdae6c847
1 changed files with 19 additions and 7 deletions
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26
src/basic/util.c
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@ -2144,7 +2144,13 @@ ssize_t loop_read(int fd, void *buf, size_t nbytes, bool do_poll) {
assert(fd >= 0);
assert(buf);
while (nbytes > 0) {
/* If called with nbytes == 0, let's call read() at least
* once, to validate the operation */
if (nbytes > (size_t) SSIZE_MAX)
return -EINVAL;
do {
ssize_t k;
k = read(fd, p, nbytes);
@ -2158,7 +2164,7 @@ ssize_t loop_read(int fd, void *buf, size_t nbytes, bool do_poll) {
* and expect that any error/EOF is reported
* via read() */
fd_wait_for_event(fd, POLLIN, USEC_INFINITY);
(void) fd_wait_for_event(fd, POLLIN, USEC_INFINITY);
continue;
}
@ -2168,10 +2174,12 @@ ssize_t loop_read(int fd, void *buf, size_t nbytes, bool do_poll) {
if (k == 0)
return n;
assert((size_t) k <= nbytes);
p += k;
nbytes -= k;
n += k;
}
} while (nbytes > 0);
return n;
}
@ -2181,9 +2189,10 @@ int loop_read_exact(int fd, void *buf, size_t nbytes, bool do_poll) {
n = loop_read(fd, buf, nbytes, do_poll);
if (n < 0)
return n;
return (int) n;
if ((size_t) n != nbytes)
return -EIO;
return 0;
}
@ -2193,7 +2202,8 @@ int loop_write(int fd, const void *buf, size_t nbytes, bool do_poll) {
assert(fd >= 0);
assert(buf);
errno = 0;
if (nbytes > (size_t) SSIZE_MAX)
return -EINVAL;
do {
ssize_t k;
@ -2208,16 +2218,18 @@ int loop_write(int fd, const void *buf, size_t nbytes, bool do_poll) {
* and expect that any error/EOF is reported
* via write() */
fd_wait_for_event(fd, POLLOUT, USEC_INFINITY);
(void) fd_wait_for_event(fd, POLLOUT, USEC_INFINITY);
continue;
}
return -errno;
}
if (nbytes > 0 && k == 0) /* Can't really happen */
if (_unlikely_(nbytes > 0 && k == 0)) /* Can't really happen */
return -EIO;
assert((size_t) k <= nbytes);
p += k;
nbytes -= k;
} while (nbytes > 0);