treewide: sanitize loop_write

loop_write() didn't follow the usual systemd rules and returned status
partially in errno and required extensive checks from callers. Some of
the callers dealt with this properly, but many did not, treating
partial writes as successful. Simplify things by conforming to usual rules.

13 files changed, 51 insertions, 77 deletions

diff --git a/src/core/ima-setup.c b/src/core/ima-setup.c
index 3416802bcb..3470ca1768 100644
--- a/src/core/ima-setup.c
+++ b/src/core/ima-setup.c
@@ -42,13 +42,13 @@
 #define IMA_POLICY_PATH "/etc/ima/ima-policy"
 
 int ima_setup(void) {
+        int r = 0;
 
 #ifdef HAVE_IMA
         struct stat st;
-        ssize_t policy_size = 0, written = 0;
+        ssize_t policy_size = 0;
         char *policy;
         _cleanup_close_ int policyfd = -1, imafd = -1;
-        int result = 0;
 
         if (stat(IMA_POLICY_PATH, &st) < 0)
                 return 0;
@@ -81,13 +81,13 @@ int ima_setup(void) {
         policy = mmap(NULL, policy_size, PROT_READ, MAP_PRIVATE, policyfd, 0);
         if (policy == MAP_FAILED) {
                 log_error_errno(errno, "mmap() failed (%m), freezing");
-                result = -errno;
+                r = -errno;
                 goto out;
         }
 
-        written = loop_write(imafd, policy, (size_t)policy_size, false);
-        if (written != policy_size) {
-                log_error_errno(errno, "Failed to load the IMA custom policy file %s (%m), ignoring.",
+        r = loop_write(imafd, policy, (size_t)policy_size, false);
+        if (r < 0) {
+                log_error_errno(r, "Failed to load the IMA custom policy file %s (%m), ignoring.",
                                 IMA_POLICY_PATH);
                 goto out_mmap;
         }
@@ -97,9 +97,6 @@ int ima_setup(void) {
 out_mmap:
         munmap(policy, policy_size);
 out:
-        if (result)
-                 return result;
 #endif /* HAVE_IMA */
-
-        return 0;
+        return r;
 }
diff --git a/src/core/machine-id-setup.c b/src/core/machine-id-setup.c
index 74582a5dcd..d91a02cf15 100644
--- a/src/core/machine-id-setup.c
+++ b/src/core/machine-id-setup.c
@@ -182,7 +182,7 @@ static int write_machine_id(int fd, char id[34]) {
         assert(id);
         lseek(fd, 0, SEEK_SET);
 
-        if (loop_write(fd, id, 33, false) == 33)
+        if (loop_write(fd, id, 33, false) == 0)
                 return 0;
 
         return -errno;
@@ -329,10 +329,9 @@ int machine_id_setup(const char *root) {
         if (r < 0)
                 return r;
 
-        if (S_ISREG(st.st_mode) && writable) {
+        if (S_ISREG(st.st_mode) && writable)
                 if (write_machine_id(fd, id) == 0)
                         return 0;
-        }
 
         fd = safe_close(fd);
 
diff --git a/src/journal/compress.c b/src/journal/compress.c
index c4c715be2f..9440fcd60e 100644
--- a/src/journal/compress.c
+++ b/src/journal/compress.c
@@ -400,12 +400,9 @@ int compress_stream_xz(int fdf, int fdt, off_t max_bytes) {
 
                         n = sizeof(out) - s.avail_out;
 
-                        errno = 0;
                         k = loop_write(fdt, out, n, false);
                         if (k < 0)
                                 return k;
-                        if (k != n)
-                                return errno ? -errno : -EIO;
 
                         if (ret == LZMA_STREAM_END) {
                                 log_debug("XZ compression finished (%"PRIu64" -> %"PRIu64" bytes, %.1f%%)",
@@ -478,8 +475,6 @@ int compress_stream_lz4(int fdf, int fdt, off_t max_bytes) {
                 n = loop_write(fdt, out, r, false);
                 if (n < 0)
                         return n;
-                if (n != r)
-                        return errno ? -errno : -EIO;
 
                 total_out += sizeof(header) + r;
 
@@ -559,12 +554,9 @@ int decompress_stream_xz(int fdf, int fdt, off_t max_bytes) {
                                 max_bytes -= n;
                         }
 
-                        errno = 0;
                         k = loop_write(fdt, out, n, false);
                         if (k < 0)
                                 return k;
-                        if (k != n)
-                                return errno ? -errno : -EIO;
 
                         if (ret == LZMA_STREAM_END) {
                                 log_debug("XZ decompression finished (%"PRIu64" -> %"PRIu64" bytes, %.1f%%)",
@@ -645,12 +637,9 @@ int decompress_stream_lz4(int fdf, int fdt, off_t max_bytes) {
                         return -EFBIG;
                 }
 
-                errno = 0;
                 n = loop_write(fdt, out, r, false);
                 if (n < 0)
                         return n;
-                if (n != r)
-                        return errno ? -errno : -EIO;
         }
 
         log_debug("LZ4 decompression finished (%zu -> %zu bytes, %.1f%%)",
diff --git a/src/journal/journal-send.c b/src/journal/journal-send.c
index 887b957c4d..56a96c55dd 100644
--- a/src/journal/journal-send.c
+++ b/src/journal/journal-send.c
@@ -453,13 +453,10 @@ _public_ int sd_journal_stream_fd(const char *identifier, int priority, int leve
         header[l++] = '0';
         header[l++] = '\n';
 
-        r = (int) loop_write(fd, header, l, false);
+        r = loop_write(fd, header, l, false);
         if (r < 0)
                 return r;
 
-        if ((size_t) r != l)
-                return -errno;
-
         r = fd;
         fd = -1;
         return r;
diff --git a/src/journal/journalctl.c b/src/journal/journalctl.c
index 3cec9a0c84..b2f6966fca 100644
--- a/src/journal/journalctl.c
+++ b/src/journal/journalctl.c
@@ -1406,17 +1406,15 @@ static int setup_keys(void) {
         h.fsprg_secpar = htole16(FSPRG_RECOMMENDED_SECPAR);
         h.fsprg_state_size = htole64(state_size);
 
-        l = loop_write(fd, &h, sizeof(h), false);
-        if (l < 0 || (size_t) l != sizeof(h)) {
-                log_error_errno(EIO, "Failed to write header: %m");
-                r = -EIO;
+        r = loop_write(fd, &h, sizeof(h), false);
+        if (r < 0) {
+                log_error_errno(r, "Failed to write header: %m");
                 goto finish;
         }
 
-        l = loop_write(fd, state, state_size, false);
-        if (l < 0 || (size_t) l != state_size) {
-                log_error_errno(EIO, "Failed to write state: %m");
-                r = -EIO;
+        r = loop_write(fd, state, state_size, false);
+        if (r < 0) {
+                log_error_errno(r, "Failed to write state: %m");
                 goto finish;
         }
 
diff --git a/src/libsystemd-terminal/subterm.c b/src/libsystemd-terminal/subterm.c
index 75a25e5590..78efc9d7c0 100644
--- a/src/libsystemd-terminal/subterm.c
+++ b/src/libsystemd-terminal/subterm.c
@@ -117,14 +117,14 @@ static int output_winch(Output *o) {
 }
 
 static int output_flush(Output *o) {
-        ssize_t len;
+        int r;
 
         if (o->n_obuf < 1)
                 return 0;
 
-        len = loop_write(o->fd, o->obuf, o->n_obuf, false);
-        if (len < 0)
-                return log_error_errno(len, "error: cannot write to TTY (%zd): %m", len);
+        r = loop_write(o->fd, o->obuf, o->n_obuf, false);
+        if (r < 0)
+                return log_error_errno(r, "error: cannot write to TTY: %m");
 
         o->n_obuf = 0;
 
diff --git a/src/random-seed/random-seed.c b/src/random-seed/random-seed.c
index 40eaaf46d9..06c1239601 100644
--- a/src/random-seed/random-seed.c
+++ b/src/random-seed/random-seed.c
@@ -113,12 +113,9 @@ int main(int argc, char *argv[]) {
                 } else {
                         lseek(seed_fd, 0, SEEK_SET);
 
-                        k = loop_write(random_fd, buf, (size_t) k, false);
-                        if (k <= 0) {
-                                log_error("Failed to write seed to /dev/urandom: %s", r < 0 ? strerror(-r) : "short write");
-
-                                r = k == 0 ? -EIO : (int) k;
-                        }
+                        r = loop_write(random_fd, buf, (size_t) k, false);
+                        if (r < 0)
+                                log_error_errno(r, "Failed to write seed to /dev/urandom: %m");
                 }
 
         } else if (streq(argv[1], "save")) {
@@ -155,10 +152,8 @@ int main(int argc, char *argv[]) {
                 r = k == 0 ? -EIO : (int) k;
         } else {
                 r = loop_write(seed_fd, buf, (size_t) k, false);
-                if (r <= 0) {
-                        log_error("Failed to write new random seed file: %s", r < 0 ? strerror(-r) : "short write");
-                        r = r == 0 ? -EIO : r;
-                }
+                if (r < 0)
+                        log_error_errno(r, "Failed to write new random seed file: %m");
         }
 
 finish:
diff --git a/src/shared/copy.c b/src/shared/copy.c
index abb7fbc52b..b8b1ba1866 100644
--- a/src/shared/copy.c
+++ b/src/shared/copy.c
@@ -63,7 +63,7 @@ int copy_bytes(int fdf, int fdt, off_t max_bytes) {
                 /* As a fallback just copy bits by hand */
                 {
                         char buf[m];
-                        ssize_t k;
+                        int r;
 
                         n = read(fdf, buf, m);
                         if (n < 0)
@@ -71,12 +71,9 @@ int copy_bytes(int fdf, int fdt, off_t max_bytes) {
                         if (n == 0) /* EOF */
                                 break;
 
-                        errno = 0;
-                        k = loop_write(fdt, buf, n, false);
-                        if (k < 0)
-                                return k;
-                        if (k != n)
-                                return errno ? -errno : -EIO;
+                        r = loop_write(fdt, buf, n, false);
+                        if (r < 0)
+                                return r;
 
                 }
 
diff --git a/src/shared/util.c b/src/shared/util.c
index ff8835b72d..26a4f72b43 100644
--- a/src/shared/util.c
+++ b/src/shared/util.c
@@ -2292,13 +2292,15 @@ ssize_t loop_read(int fd, void *buf, size_t nbytes, bool do_poll) {
         return n;
 }
 
-ssize_t loop_write(int fd, const void *buf, size_t nbytes, bool do_poll) {
+int loop_write(int fd, const void *buf, size_t nbytes, bool do_poll) {
         const uint8_t *p = buf;
         ssize_t n = 0;
 
         assert(fd >= 0);
         assert(buf);
 
+        errno = 0;
+
         while (nbytes > 0) {
                 ssize_t k;
 
@@ -2317,14 +2319,15 @@ ssize_t loop_write(int fd, const void *buf, size_t nbytes, bool do_poll) {
                 }
 
                 if (k <= 0)
-                        return n > 0 ? n : (k < 0 ? -errno : 0);
+                        /* We were not done yet, and a write error occured. */
+                        return errno ? -errno : -EIO;
 
                 p += k;
                 nbytes -= k;
                 n += k;
         }
 
-        return n;
+        return 0;
 }
 
 int parse_size(const char *t, off_t base, off_t *size) {
diff --git a/src/shared/util.h b/src/shared/util.h
index 61094cca2f..73bd9012fd 100644
--- a/src/shared/util.h
+++ b/src/shared/util.h
@@ -425,7 +425,7 @@ int sigaction_many(const struct sigaction *sa, ...);
 int fopen_temporary(const char *path, FILE **_f, char **_temp_path);
 
 ssize_t loop_read(int fd, void *buf, size_t nbytes, bool do_poll);
-ssize_t loop_write(int fd, const void *buf, size_t nbytes, bool do_poll);
+int loop_write(int fd, const void *buf, size_t nbytes, bool do_poll);
 
 bool is_device_path(const char *path);
 
diff --git a/src/systemctl/systemctl.c b/src/systemctl/systemctl.c
index d356686f78..6e48671ee6 100644
--- a/src/systemctl/systemctl.c
+++ b/src/systemctl/systemctl.c
@@ -7246,12 +7246,9 @@ static int talk_initctl(void) {
                 return -errno;
         }
 
-        errno = 0;
-        r = loop_write(fd, &request, sizeof(request), false) != sizeof(request);
-        if (r) {
-                log_error_errno(errno, "Failed to write to "INIT_FIFO": %m");
-                return errno > 0 ? -errno : -EIO;
-        }
+        r = loop_write(fd, &request, sizeof(request), false);
+        if (r < 0)
+                return log_error_errno(r, "Failed to write to "INIT_FIFO": %m");
 
         return 1;
 }
diff --git a/src/tty-ask-password-agent/tty-ask-password-agent.c b/src/tty-ask-password-agent/tty-ask-password-agent.c
index fa8448cfae..5fc27f9ae5 100644
--- a/src/tty-ask-password-agent/tty-ask-password-agent.c
+++ b/src/tty-ask-password-agent/tty-ask-password-agent.c
@@ -103,9 +103,9 @@ static int ask_password_plymouth(
         if (!packet)
                 return log_oom();
 
-        k = loop_write(fd, packet, n + 1, true);
-        if (k != n + 1)
-                return k < 0 ? (int) k : -EIO;
+        r = loop_write(fd, packet, n + 1, true);
+        if (r < 0)
+                return r;
 
         pollfd[POLL_SOCKET].fd = fd;
         pollfd[POLL_SOCKET].events = POLLIN;
@@ -165,9 +165,9 @@ static int ask_password_plymouth(
                                 if (asprintf(&packet, "*\002%c%s%n", (int) (strlen(message) + 1), message, &n) < 0)
                                         return -ENOMEM;
 
-                                k = loop_write(fd, packet, n+1, true);
-                                if (k != n + 1)
-                                        return k < 0 ? (int) k : -EIO;
+                                r = loop_write(fd, packet, n+1, true);
+                                if (r < 0)
+                                        return r;
 
                                 accept_cached = false;
                                 p = 0;
diff --git a/src/vconsole/vconsole-setup.c b/src/vconsole/vconsole-setup.c
index b7a536b983..28371711b6 100644
--- a/src/vconsole/vconsole-setup.c
+++ b/src/vconsole/vconsole-setup.c
@@ -54,8 +54,9 @@ static int disable_utf8(int fd) {
         if (ioctl(fd, KDSKBMODE, K_XLATE) < 0)
                 r = -errno;
 
-        if (loop_write(fd, "\033%@", 3, false) < 0)
-                r = -errno;
+        k = loop_write(fd, "\033%@", 3, false);
+        if (k < 0)
+                r = k;
 
         k = write_string_file("/sys/module/vt/parameters/default_utf8", "0");
         if (k < 0)
@@ -86,8 +87,9 @@ static int enable_utf8(int fd) {
                         r = -errno;
         }
 
-        if (loop_write(fd, "\033%G", 3, false) < 0)
-                r = -errno;
+        k = loop_write(fd, "\033%G", 3, false);
+        if (k < 0)
+                r = k;
 
         k = write_string_file("/sys/module/vt/parameters/default_utf8", "1");
         if (k < 0)