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linux: refactor /proc file reader logic

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Move common logic into a separate function that will be reused in a
follow-up commit. This commit also adds a minor correctness fix in
that the `read(2)` system call is now retried on `EINTR`.

PR-URL: https://github.com/libuv/libuv/pull/2876
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
This commit is contained in:
Ben Noordhuis 2020-06-12 12:15:38 +02:00
parent 2967557b66
commit 1a89003635
1 changed files with 38 additions and 45 deletions
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83
src/unix/linux-core.c
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@ -982,43 +982,51 @@ void uv__set_process_title(const char* title) {
}
static uint64_t uv__read_proc_meminfo(const char* what) {
uint64_t rc;
static int uv__slurp(const char* filename, char* buf, size_t len) {
ssize_t n;
char* p;
int fd;
char buf[4096]; /* Large enough to hold all of /proc/meminfo. */
rc = 0;
fd = uv__open_cloexec("/proc/meminfo", O_RDONLY);
assert(len > 0);
fd = uv__open_cloexec(filename, O_RDONLY);
if (fd < 0)
return 0;
return fd;
n = read(fd, buf, sizeof(buf) - 1);
if (n <= 0)
goto out;
buf[n] = '\0';
p = strstr(buf, what);
if (p == NULL)
goto out;
p += strlen(what);
if (1 != sscanf(p, "%" PRIu64 " kB", &rc))
goto out;
rc *= 1024;
out:
do
n = read(fd, buf, len - 1);
while (n == -1 && errno == EINTR);
if (uv__close_nocheckstdio(fd))
abort();
return rc;
if (n < 0)
return UV__ERR(errno);
buf[n] = '\0';
return 0;
}
static uint64_t uv__read_proc_meminfo(const char* what) {
uint64_t rc;
char* p;
char buf[4096]; /* Large enough to hold all of /proc/meminfo. */
if (uv__slurp("/proc/meminfo", buf, sizeof(buf)))
return 0;
p = strstr(buf, what);
if (p == NULL)
return 0;
p += strlen(what);
rc = 0;
sscanf(p, "%" PRIu64 " kB", &rc);
return rc * 1024;
}
@ -1056,28 +1064,13 @@ uint64_t uv_get_total_memory(void) {
static uint64_t uv__read_cgroups_uint64(const char* cgroup, const char* param) {
char filename[256];
uint64_t rc;
int fd;
ssize_t n;
char buf[32]; /* Large enough to hold an encoded uint64_t. */
snprintf(filename, 256, "/sys/fs/cgroup/%s/%s", cgroup, param);
uint64_t rc;
rc = 0;
fd = uv__open_cloexec(filename, O_RDONLY);
if (fd < 0)
return 0;
n = read(fd, buf, sizeof(buf) - 1);
if (n > 0) {
buf[n] = '\0';
snprintf(filename, sizeof(filename), "/sys/fs/cgroup/%s/%s", cgroup, param);
if (0 == uv__slurp(filename, buf, sizeof(buf)))
sscanf(buf, "%" PRIu64, &rc);
}
if (uv__close_nocheckstdio(fd))
abort();
return rc;
}