alloc-util: simplify GREEDY_REALLOC() logic by relying on malloc_usable_size()

We recently started making more use of malloc_usable_size() and rely on
it (see the string_erase() story). Given that we don't really support
sytems where malloc_usable_size() cannot be trusted beyond statistics
anyway, let's go fully in and rework GREEDY_REALLOC() on top of it:
instead of passing around and maintaining the currenly allocated size
everywhere, let's just derive it automatically from
malloc_usable_size().

I am mostly after this for the simplicity this brings. It also brings
minor efficiency improvements I guess, but things become so much nicer
to look at if we can avoid these allocation size variables everywhere.

Note that the malloc_usable_size() man page says relying on it wasn't
"good programming practice", but I think it does this for reasons that
don't apply here: the greedy realloc logic specifically doesn't rely on
the returned extra size, beyond the fact that it is equal or larger than
what was requested.

(This commit was supposed to be a quick patch btw, but apparently we use
the greedy realloc stuff quite a bit across the codebase, so this ends
up touching *a*lot* of code.)

1 files changed, 19 insertions, 19 deletions

diff --git a/src/shared/journal-importer.c b/src/shared/journal-importer.c
index b2785f0552..0d82acc25c 100644
--- a/src/shared/journal-importer.c
+++ b/src/shared/journal-importer.c
@@ -1,6 +1,7 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 
 #include <errno.h>
+#include <malloc.h>
 #include <unistd.h>
 
 #include "alloc-util.h"
@@ -37,7 +38,7 @@ void journal_importer_cleanup(JournalImporter *imp) {
 static char* realloc_buffer(JournalImporter *imp, size_t size) {
         char *b, *old = imp->buf;
 
-        b = GREEDY_REALLOC(imp->buf, imp->size, size);
+        b = GREEDY_REALLOC(imp->buf, size);
         if (!b)
                 return NULL;
 
@@ -53,8 +54,7 @@ static int get_line(JournalImporter *imp, char **line, size_t *size) {
         assert(imp);
         assert(imp->state == IMPORTER_STATE_LINE);
         assert(imp->offset <= imp->filled);
-        assert(imp->filled <= imp->size);
-        assert(!imp->buf || imp->size > 0);
+        assert(imp->filled <= MALLOC_SIZEOF_SAFE(imp->buf));
         assert(imp->fd >= 0);
 
         for (;;) {
@@ -80,22 +80,22 @@ static int get_line(JournalImporter *imp, char **line, size_t *size) {
                 /* We know that imp->filled is at most DATA_SIZE_MAX, so if
                    we reallocate it, we'll increase the size at least a bit. */
                 assert_cc(DATA_SIZE_MAX < ENTRY_SIZE_MAX);
-                if (imp->size - imp->filled < LINE_CHUNK &&
+                if (MALLOC_SIZEOF_SAFE(imp->buf) - imp->filled < LINE_CHUNK &&
                     !realloc_buffer(imp, MIN(imp->filled + LINE_CHUNK, ENTRY_SIZE_MAX)))
                                 return log_oom();
 
                 assert(imp->buf);
-                assert(imp->size - imp->filled >= LINE_CHUNK ||
-                       imp->size == ENTRY_SIZE_MAX);
+                assert(MALLOC_SIZEOF_SAFE(imp->buf) - imp->filled >= LINE_CHUNK ||
+                       MALLOC_SIZEOF_SAFE(imp->buf) >= ENTRY_SIZE_MAX);
 
                 n = read(imp->fd,
                          imp->buf + imp->filled,
-                         imp->size - imp->filled);
+                         MALLOC_SIZEOF_SAFE(imp->buf) - imp->filled);
                 if (n < 0) {
                         if (errno != EAGAIN)
                                 log_error_errno(errno, "read(%d, ..., %zu): %m",
                                                 imp->fd,
-                                                imp->size - imp->filled);
+                                                MALLOC_SIZEOF_SAFE(imp->buf) - imp->filled);
                         return -errno;
                 } else if (n == 0)
                         return 0;
@@ -116,9 +116,7 @@ static int fill_fixed_size(JournalImporter *imp, void **data, size_t size) {
         assert(IN_SET(imp->state, IMPORTER_STATE_DATA_START, IMPORTER_STATE_DATA, IMPORTER_STATE_DATA_FINISH));
         assert(size <= DATA_SIZE_MAX);
         assert(imp->offset <= imp->filled);
-        assert(imp->filled <= imp->size);
-        assert(imp->buf || imp->size == 0);
-        assert(!imp->buf || imp->size > 0);
+        assert(imp->filled <= MALLOC_SIZEOF_SAFE(imp->buf));
         assert(imp->fd >= 0);
         assert(data);
 
@@ -133,11 +131,11 @@ static int fill_fixed_size(JournalImporter *imp, void **data, size_t size) {
                         return log_oom();
 
                 n = read(imp->fd, imp->buf + imp->filled,
-                         imp->size - imp->filled);
+                         MALLOC_SIZEOF_SAFE(imp->buf) - imp->filled);
                 if (n < 0) {
                         if (errno != EAGAIN)
                                 log_error_errno(errno, "read(%d, ..., %zu): %m", imp->fd,
-                                                imp->size - imp->filled);
+                                                MALLOC_SIZEOF_SAFE(imp->buf) - imp->filled);
                         return -errno;
                 } else if (n == 0)
                         return 0;
@@ -431,7 +429,7 @@ int journal_importer_push_data(JournalImporter *imp, const char *data, size_t si
                 return log_error_errno(SYNTHETIC_ERRNO(ENOMEM),
                                        "Failed to store received data of size %zu "
                                        "(in addition to existing %zu bytes with %zu filled): %s",
-                                       size, imp->size, imp->filled,
+                                       size, MALLOC_SIZEOF_SAFE(imp->buf), imp->filled,
                                        strerror_safe(ENOMEM));
 
         memcpy(imp->buf + imp->filled, data, size);
@@ -452,18 +450,21 @@ void journal_importer_drop_iovw(JournalImporter *imp) {
 
         if (remain == 0) /* no brainer */
                 imp->offset = imp->scanned = imp->filled = 0;
-        else if (imp->offset > imp->size - imp->filled &&
+        else if (imp->offset > MALLOC_SIZEOF_SAFE(imp->buf) - imp->filled &&
                  imp->offset > remain) {
                 memcpy(imp->buf, imp->buf + imp->offset, remain);
                 imp->offset = imp->scanned = 0;
                 imp->filled = remain;
         }
 
-        target = imp->size;
+        target = MALLOC_SIZEOF_SAFE(imp->buf);
         while (target > 16 * LINE_CHUNK && imp->filled < target / 2)
                 target /= 2;
-        if (target < imp->size) {
+        if (target < MALLOC_SIZEOF_SAFE(imp->buf)) {
                 char *tmp;
+                size_t old_size;
+
+                old_size = MALLOC_SIZEOF_SAFE(imp->buf);
 
                 tmp = realloc(imp->buf, target);
                 if (!tmp)
@@ -471,9 +472,8 @@ void journal_importer_drop_iovw(JournalImporter *imp) {
                                     target);
                 else {
                         log_debug("Reallocated buffer from %zu to %zu bytes",
-                                  imp->size, target);
+                                  old_size, target);
                         imp->buf = tmp;
-                        imp->size = target;
                 }
         }
 }