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[Fix] Fix return value and errno handling in syscalls.c.
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Fixes: zhanghai#789
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@zhanghai
zhanghai committed May 14, 2022
1 parent e356a9c commit 95bd2d2
Showing 1 changed file with 36 additions and 17 deletions.
53 changes: 36 additions & 17 deletions app/src/main/jni/syscalls.c
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Original file line number Diff line number Diff line change
Expand Up @@ -35,21 +35,39 @@
#define LOG_TAG "syscalls"

#undef TEMP_FAILURE_RETRY
// Checks errno when return value is -1.
#define TEMP_FAILURE_RETRY(exp) ({ \
__typeof__(exp) _rc; \
do { \
errno = 0; \
_rc = (exp); \
} while (errno == EINTR); \
} while (_rc == -1 && errno == EINTR); \
if (_rc != -1) { \
errno = 0; \
} \
_rc; })

#define TEMP_FAILURE_RETRY_R(exp) ({ \
// Checks return value as errno.
#define TEMP_FAILURE_RETRY_E(exp) ({ \
__typeof__(exp) _rc; \
do { \
_rc = (exp); \
} while (_rc == EINTR); \
_rc; })

// Checks errno when return value is NULL.
#define TEMP_FAILURE_RETRY_N(exp) ({ \
__typeof__(exp) _rc; \
do { \
errno = 0; \
_rc = (exp); \
} while (!_rc && errno == EINTR); \
if (_rc) { \
errno = 0; \
} \
_rc; })

// Always checks errno and ignores return value.
#define TEMP_FAILURE_RETRY_V(exp) ({ \
do { \
errno = 0; \
Expand Down Expand Up @@ -407,7 +425,8 @@ JNIEXPORT void JNICALL
Java_me_zhanghai_android_files_provider_linux_syscall_Syscalls_endmntent(
JNIEnv *env, jclass clazz, jlong javaFile) {
FILE *file = (FILE *) javaFile;
TEMP_FAILURE_RETRY(endmntent(file));
// The endmntent() function always returns 1.
TEMP_FAILURE_RETRY_V(endmntent(file));
if (errno) {
throwSyscallException(env, "endmntent");
}
Expand Down Expand Up @@ -574,7 +593,7 @@ JNIEXPORT jobject JNICALL
Java_me_zhanghai_android_files_provider_linux_syscall_Syscalls_getgrent(JNIEnv *env, jclass clazz) {
while (true) {
// getgrent() in bionic is thread safe.
struct group *group = TEMP_FAILURE_RETRY(getgrent());
struct group *group = TEMP_FAILURE_RETRY_N(getgrent());
if (errno) {
throwSyscallException(env, "getgrent");
return NULL;
Expand Down Expand Up @@ -612,7 +631,7 @@ Java_me_zhanghai_android_files_provider_linux_syscall_Syscalls_getgrgid(
char buffer[bufferSize];
struct group group = {};
struct group *result = NULL;
errno = TEMP_FAILURE_RETRY_R(getgrgid_r(gid, &group, buffer, bufferSize, &result));
errno = TEMP_FAILURE_RETRY_E(getgrgid_r(gid, &group, buffer, bufferSize, &result));
if (errno) {
throwSyscallException(env, "getgrgid_r");
return NULL;
Expand All @@ -623,7 +642,7 @@ Java_me_zhanghai_android_files_provider_linux_syscall_Syscalls_getgrgid(
return newStructGroup(env, result);
#else
gid_t gid = (gid_t) javaGid;
struct group *result = TEMP_FAILURE_RETRY(getgrgid(gid));
struct group *result = TEMP_FAILURE_RETRY_N(getgrgid(gid));
if (errno) {
throwSyscallException(env, "getgrgid");
return NULL;
Expand All @@ -649,7 +668,7 @@ Java_me_zhanghai_android_files_provider_linux_syscall_Syscalls_getgrnam(
char buffer[bufferSize];
struct group group = {};
struct group *result = NULL;
errno = TEMP_FAILURE_RETRY_R(getgrnam_r(name, &group, buffer, bufferSize, &result));
errno = TEMP_FAILURE_RETRY_E(getgrnam_r(name, &group, buffer, bufferSize, &result));
free(name);
if (errno) {
throwSyscallException(env, "getgrnam_r");
Expand All @@ -661,7 +680,7 @@ Java_me_zhanghai_android_files_provider_linux_syscall_Syscalls_getgrnam(
return newStructGroup(env, result);
#else
char *name = mallocStringFromByteString(env, javaName);
struct group *result = TEMP_FAILURE_RETRY(getgrnam(name));
struct group *result = TEMP_FAILURE_RETRY_N(getgrnam(name));
free(name);
if (errno) {
throwSyscallException(env, "getgrnam");
Expand Down Expand Up @@ -737,12 +756,12 @@ Java_me_zhanghai_android_files_provider_linux_syscall_Syscalls_getmntent(
FILE *file = (FILE *) javaFile;
#if __ANDROID_API__ >= __ANDROID_API_L_MR1__
// getmntent() in bionic is thread safe.
struct mntent *mntent = TEMP_FAILURE_RETRY(getmntent(file));
struct mntent *mntent = TEMP_FAILURE_RETRY_N(getmntent(file));
#else
// getmntent() in bionic is a stub until API 22.
struct mntent entryBuffer = {};
char stringsBuffer[BUFSIZ] = {};
struct mntent *mntent = TEMP_FAILURE_RETRY(_getmntent_r(file, &entryBuffer, stringsBuffer,
struct mntent *mntent = TEMP_FAILURE_RETRY_N(_getmntent_r(file, &entryBuffer, stringsBuffer,
sizeof(stringsBuffer)));
#endif
if (errno) {
Expand Down Expand Up @@ -814,7 +833,7 @@ JNIEXPORT jobject JNICALL
Java_me_zhanghai_android_files_provider_linux_syscall_Syscalls_getpwent(JNIEnv *env, jclass clazz) {
while (true) {
// getpwent() in bionic is thread safe.
struct passwd *passwd = TEMP_FAILURE_RETRY(getpwent());
struct passwd *passwd = TEMP_FAILURE_RETRY_N(getpwent());
if (errno) {
throwSyscallException(env, "getpwent");
return NULL;
Expand Down Expand Up @@ -846,7 +865,7 @@ Java_me_zhanghai_android_files_provider_linux_syscall_Syscalls_getpwnam(
char buffer[bufferSize];
struct passwd passwd = {};
struct passwd *result = NULL;
errno = TEMP_FAILURE_RETRY_R(getpwnam_r(name, &passwd, buffer, bufferSize, &result));
errno = TEMP_FAILURE_RETRY_E(getpwnam_r(name, &passwd, buffer, bufferSize, &result));
free(name);
if (errno) {
throwSyscallException(env, "getpwnam_r");
Expand All @@ -871,7 +890,7 @@ Java_me_zhanghai_android_files_provider_linux_syscall_Syscalls_getpwuid(
char buffer[bufferSize];
struct passwd passwd = {};
struct passwd *result = NULL;
errno = TEMP_FAILURE_RETRY_R(getpwuid_r(uid, &passwd, buffer, bufferSize, &result));
errno = TEMP_FAILURE_RETRY_E(getpwuid_r(uid, &passwd, buffer, bufferSize, &result));
if (errno) {
throwSyscallException(env, "getpwnam_r");
return NULL;
Expand Down Expand Up @@ -1344,7 +1363,7 @@ JNIEXPORT jlong JNICALL
Java_me_zhanghai_android_files_provider_linux_syscall_Syscalls_opendir(
JNIEnv *env, jclass clazz, jobject javaPath) {
char *path = mallocStringFromByteString(env, javaPath);
DIR *dir = TEMP_FAILURE_RETRY(opendir(path));
DIR *dir = TEMP_FAILURE_RETRY_N(opendir(path));
free(path);
if (errno) {
throwSyscallException(env, "opendir");
Expand Down Expand Up @@ -1375,7 +1394,7 @@ JNIEXPORT jobject JNICALL
Java_me_zhanghai_android_files_provider_linux_syscall_Syscalls_readdir(
JNIEnv *env, jclass clazz, jlong javaDir) {
DIR *dir = (DIR *) javaDir;
struct dirent64 *dirent = TEMP_FAILURE_RETRY(readdir64(dir));
struct dirent64 *dirent = TEMP_FAILURE_RETRY_N(readdir64(dir));
if (errno) {
throwSyscallException(env, "readdir64");
return NULL;
Expand Down Expand Up @@ -1419,7 +1438,7 @@ Java_me_zhanghai_android_files_provider_linux_syscall_Syscalls_realpath(
JNIEnv *env, jclass clazz, jobject javaPath) {
char *path = mallocStringFromByteString(env, javaPath);
char resolvedPath[PATH_MAX] = {};
TEMP_FAILURE_RETRY(realpath(path, resolvedPath));
TEMP_FAILURE_RETRY_N(realpath(path, resolvedPath));
free(path);
if (errno) {
throwSyscallException(env, "realpath");
Expand Down Expand Up @@ -1491,7 +1510,7 @@ Java_me_zhanghai_android_files_provider_linux_syscall_Syscalls_setmntent(
JNIEnv *env, jclass clazz, jobject javaPath, jobject javaMode) {
char *path = mallocStringFromByteString(env, javaPath);
char *mode = mallocStringFromByteString(env, javaMode);
FILE *file = TEMP_FAILURE_RETRY(setmntent(path, mode));
FILE *file = TEMP_FAILURE_RETRY_N(setmntent(path, mode));
free(path);
free(mode);
if (errno) {
Expand Down

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