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

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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.)
This commit is contained in:
Lennart Poettering
2021-05-19 16:42:37 +02:00
parent 99480504d4
commit 319a4f4bc4
127 changed files with 658 additions and 688 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/shared/json.c
+15 -15
View File
@@ -2399,7 +2399,7 @@ static int unhex_ucs2(const char *c, uint16_t *ret) {
static int json_parse_string(const char **p, char **ret) {
_cleanup_free_ char *s = NULL;
size_t n = 0, allocated = 0;
size_t n = 0;
const char *c;
assert(p);
@@ -2471,7 +2471,7 @@ static int json_parse_string(const char **p, char **ret) {
c += 5;
if (!GREEDY_REALLOC(s, allocated, n + 5))
if (!GREEDY_REALLOC(s, n + 5))
return -ENOMEM;
if (!utf16_is_surrogate(x))
@@ -2500,7 +2500,7 @@ static int json_parse_string(const char **p, char **ret) {
} else
return -EINVAL;
if (!GREEDY_REALLOC(s, allocated, n + 2))
if (!GREEDY_REALLOC(s, n + 2))
return -ENOMEM;
s[n++] = ch;
@@ -2512,7 +2512,7 @@ static int json_parse_string(const char **p, char **ret) {
if (len < 0)
return len;
if (!GREEDY_REALLOC(s, allocated, n + len + 1))
if (!GREEDY_REALLOC(s, n + len + 1))
return -ENOMEM;
memcpy(s + n, c, len);
@@ -2825,7 +2825,7 @@ typedef enum JsonExpect {
typedef struct JsonStack {
JsonExpect expect;
JsonVariant **elements;
size_t n_elements, n_elements_allocated;
size_t n_elements;
unsigned line_before;
unsigned column_before;
size_t n_suppress; /* When building: if > 0, suppress this many subsequent elements. If == SIZE_MAX, suppress all subsequent elements */
@@ -2847,7 +2847,7 @@ static int json_parse_internal(
unsigned *column,
bool continue_end) {
size_t n_stack = 1, n_stack_allocated = 0, i;
size_t n_stack = 1, i;
unsigned line_buffer = 0, column_buffer = 0;
void *tokenizer_state = NULL;
JsonStack *stack = NULL;
@@ -2859,7 +2859,7 @@ static int json_parse_internal(
p = *input;
if (!GREEDY_REALLOC(stack, n_stack_allocated, n_stack))
if (!GREEDY_REALLOC(stack, n_stack))
return -ENOMEM;
stack[0] = (JsonStack) {
@@ -2933,7 +2933,7 @@ static int json_parse_internal(
goto finish;
}
if (!GREEDY_REALLOC(stack, n_stack_allocated, n_stack+1)) {
if (!GREEDY_REALLOC(stack, n_stack+1)) {
r = -ENOMEM;
goto finish;
}
@@ -2984,7 +2984,7 @@ static int json_parse_internal(
goto finish;
}
if (!GREEDY_REALLOC(stack, n_stack_allocated, n_stack+1)) {
if (!GREEDY_REALLOC(stack, n_stack+1)) {
r = -ENOMEM;
goto finish;
}
@@ -3168,7 +3168,7 @@ static int json_parse_internal(
(void) json_variant_set_source(&add, source, line_token, column_token);
if (!GREEDY_REALLOC(current->elements, current->n_elements_allocated, current->n_elements + 1)) {
if (!GREEDY_REALLOC(current->elements, current->n_elements + 1)) {
r = -ENOMEM;
goto finish;
}
@@ -3229,12 +3229,12 @@ int json_parse_file_at(FILE *f, int dir_fd, const char *path, JsonParseFlags fla
int json_buildv(JsonVariant **ret, va_list ap) {
JsonStack *stack = NULL;
size_t n_stack = 1, n_stack_allocated = 0, i;
size_t n_stack = 1, i;
int r;
assert_return(ret, -EINVAL);
if (!GREEDY_REALLOC(stack, n_stack_allocated, n_stack))
if (!GREEDY_REALLOC(stack, n_stack))
return -ENOMEM;
stack[0] = (JsonStack) {
@@ -3517,7 +3517,7 @@ int json_buildv(JsonVariant **ret, va_list ap) {
goto finish;
}
if (!GREEDY_REALLOC(stack, n_stack_allocated, n_stack+1)) {
if (!GREEDY_REALLOC(stack, n_stack+1)) {
r = -ENOMEM;
goto finish;
}
@@ -3714,7 +3714,7 @@ int json_buildv(JsonVariant **ret, va_list ap) {
goto finish;
}
if (!GREEDY_REALLOC(stack, n_stack_allocated, n_stack+1)) {
if (!GREEDY_REALLOC(stack, n_stack+1)) {
r = -ENOMEM;
goto finish;
}
@@ -3810,7 +3810,7 @@ int json_buildv(JsonVariant **ret, va_list ap) {
/* If a variant was generated, add it to our current variant, but only if we are not supposed to suppress additions */
if (add && current->n_suppress == 0) {
if (!GREEDY_REALLOC(current->elements, current->n_elements_allocated, current->n_elements + 1)) {
if (!GREEDY_REALLOC(current->elements, current->n_elements + 1)) {
r = -ENOMEM;
goto finish;
}