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libcutils: android_get_control_file uses realpath. am: dd6eefca30

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am: 877436dd25

Change-Id: Id5bd92bd726015459840ac3a414c9efdb3c970c0
This commit is contained in:
Yifan Hong 2019-03-26 15:35:40 -07:00 • committed by android-build-merger
commit 353d08605d
1 changed files with 18 additions and 17 deletions
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35
libcutils/android_get_control_file.cpp
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@ -39,6 +39,11 @@
#include <sys/types.h>
#include <unistd.h>
#include <string>
#include <android-base/file.h>
#include <android-base/stringprintf.h>
#include "android_get_control_env.h"
int __android_get_control_from_env(const char* prefix, const char* name) {
@ -72,26 +77,22 @@ int __android_get_control_from_env(const char* prefix, const char* name) {
}
int android_get_control_file(const char* path) {
int fd = __android_get_control_from_env(ANDROID_FILE_ENV_PREFIX, path);
std::string given_path;
if (!android::base::Realpath(path, &given_path)) return -1;
// Try path, then realpath(path), as keys to get the fd from env.
auto fd = __android_get_control_from_env(ANDROID_FILE_ENV_PREFIX, path);
if (fd < 0) {
fd = __android_get_control_from_env(ANDROID_FILE_ENV_PREFIX, given_path.c_str());
if (fd < 0) return fd;
}
// Find file path from /proc and make sure it is correct
char *proc = NULL;
if (asprintf(&proc, "/proc/self/fd/%d", fd) < 0) return -1;
if (!proc) return -1;
auto proc = android::base::StringPrintf("/proc/self/fd/%d", fd);
std::string fd_path;
if (!android::base::Realpath(proc, &fd_path)) return -1;
size_t len = strlen(path);
// readlink() does not guarantee a nul byte, len+2 so we catch truncation.
char *buf = static_cast<char *>(calloc(1, len + 2));
if (!buf) {
free(proc);
return -1;
}
ssize_t ret = TEMP_FAILURE_RETRY(readlink(proc, buf, len + 1));
free(proc);
int cmp = (len != static_cast<size_t>(ret)) || strcmp(buf, path);
free(buf);
if (ret < 0) return -1;
if (cmp != 0) return -1;
if (given_path != fd_path) return -1;
// It is what we think it is
return fd;