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Remove unused snprintf count parameter
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This commit is contained in:
Logikoma
2026-08-03 16:33:09 -04:00
parent 83ff77608f
commit 0620370dd9
6 changed files with 38 additions and 71 deletions
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5
UPGRADING.md
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@@ -83,11 +83,10 @@ having visited nothing.
/* before */ /* before */
aksl_sprintf(&count, buf, "%s=%d", key, value); aksl_sprintf(&count, buf, "%s=%d", key, value);
/* after */ /* after */
aksl_snprintf(&count, buf, sizeof(buf), "%s=%d", key, value); aksl_snprintf(buf, sizeof(buf), "%s=%d", key, value);
``` ```
Truncation is `AKERR_OUTOFBOUNDS` rather than a short success, and `*count` is Truncation is `AKERR_OUTOFBOUNDS` rather than a short success.
`0` on any failure rather than `vsprintf`'s `-1`.
**`aksl_realpath` takes the destination's length.** **`aksl_realpath` takes the destination's length.**

13
include/akstdlib.h
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@@ -444,9 +444,8 @@ akerr_ErrorContext AKERR_NOIGNORE *aksl_memchr(const void *s, int c, size_t n, v
/* ====================================================================== */ /* ====================================================================== */
/** @name Formatted output /** @name Formatted output
* *
* `*count` is the byte count written excluding the terminating NUL, and is 0 on * Bounded output is checked for truncation and reports an error when the result
* every failure path -- never vsnprintf's -1, and never the length the output * does not fit.
* *would* have been.
* *
* There is no aksl_sprintf. It wrapped vsprintf, which cannot be bounded, and an * There is no aksl_sprintf. It wrapped vsprintf, which cannot be bounded, and an
* error-handling wrapper around an unbounded write is the sharp edge this * error-handling wrapper around an unbounded write is the sharp edge this
@@ -483,16 +482,15 @@ akerr_ErrorContext AKERR_NOIGNORE *aksl_fprintf(int *count, FILE *restrict strea
* written, leaving the caller to notice by comparing that against the buffer * written, leaving the caller to notice by comparing that against the buffer
* size -- the check this library exists to stop people forgetting. * size -- the check this library exists to stop people forgetting.
* *
* @param[out] count Bytes written excluding the NUL; 0 on failure. Required.
* @param[out] str Destination buffer. Required. * @param[out] str Destination buffer. Required.
* @param[in] size Size of `str` including the terminator. Must be non-zero. * @param[in] size Size of `str` including the terminator. Must be non-zero.
* @param[in] format printf format string. Required. Checked at compile time. * @param[in] format printf format string. Required. Checked at compile time.
* @throws AKERR_NULLPOINTER If any pointer is NULL. * @throws AKERR_NULLPOINTER If str or format is NULL.
* @throws AKERR_VALUE If size is 0. * @throws AKERR_VALUE If size is 0.
* @throws AKERR_OUTOFBOUNDS If the output does not fit, naming both lengths. * @throws AKERR_OUTOFBOUNDS If the output does not fit, naming both lengths.
* @return NULL on success, an error context otherwise. * @return NULL on success, an error context otherwise.
*/ */
akerr_ErrorContext AKERR_NOIGNORE *aksl_snprintf(int *count, char *restrict str, size_t size, const char *restrict format, ...) AKSL_PRINTF_FORMAT(4, 5); akerr_ErrorContext AKERR_NOIGNORE *aksl_snprintf(char *restrict str, size_t size, const char *restrict format, ...) AKSL_PRINTF_FORMAT(3, 4);
/** /**
* @brief Format into a freshly allocated string. * @brief Format into a freshly allocated string.
@@ -551,7 +549,6 @@ akerr_ErrorContext AKERR_NOIGNORE *aksl_vfprintf(int *count, FILE *restrict stre
/** /**
* @brief vsnprintf(3) into a bounded buffer. The va_list form of aksl_snprintf. * @brief vsnprintf(3) into a bounded buffer. The va_list form of aksl_snprintf.
* @param[out] count Bytes written excluding the NUL; 0 on failure. Required.
* @param[out] str Destination buffer. Required. * @param[out] str Destination buffer. Required.
* @param[in] size Size of `str` including the terminator. Must be non-zero. * @param[in] size Size of `str` including the terminator. Must be non-zero.
* @param[in] format printf format string. Required. * @param[in] format printf format string. Required.
@@ -561,7 +558,7 @@ akerr_ErrorContext AKERR_NOIGNORE *aksl_vfprintf(int *count, FILE *restrict stre
* @throws AKERR_OUTOFBOUNDS If the output does not fit. * @throws AKERR_OUTOFBOUNDS If the output does not fit.
* @return NULL on success, an error context otherwise. * @return NULL on success, an error context otherwise.
*/ */
akerr_ErrorContext AKERR_NOIGNORE *aksl_vsnprintf(int *count, char *restrict str, size_t size, const char *restrict format, va_list args); akerr_ErrorContext AKERR_NOIGNORE *aksl_vsnprintf(char *restrict str, size_t size, const char *restrict format, va_list args);
/** @} */ /** @} */

21
src/stdlib.c
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@@ -416,10 +416,6 @@ akerr_ErrorContext AKERR_NOIGNORE *aksl_fclose(FILE *stream)
* register-save state on some ABIs. akbasic's text sink ran this UB on every * register-save state on some ABIs. akbasic's text sink ran this UB on every
* line of program output without anything visibly misbehaving, which is * line of program output without anything visibly misbehaving, which is
* exactly what made it worth fixing before something did. * exactly what made it worth fixing before something did.
* - *count is written on every path. It used to be left holding vprintf's -1
* after a failure, so a caller who read the length rather than the status got
* a negative byte count out of a function that had already failed. It is now
* 0 whenever an error is raised.
* - errno is cleared before the call and read back through AKSL_ERRNO_OR, so a * - errno is cleared before the call and read back through AKSL_ERRNO_OR, so a
* failure can never be reported with a stale -- or with a zero -- status. * failure can never be reported with a stale -- or with a zero -- status.
* *
@@ -485,34 +481,31 @@ akerr_ErrorContext AKERR_NOIGNORE *aksl_fprintf(int *count, FILE *restrict strea
* *would* have written and silently drops the rest, which is the single most * *would* have written and silently drops the rest, which is the single most
* common way a bounded write goes wrong unnoticed; a caller who wanted to know * common way a bounded write goes wrong unnoticed; a caller who wanted to know
* would have had to compare the return against the buffer size by hand, which is * would have had to compare the return against the buffer size by hand, which is
* the check this library exists to stop people forgetting. *count is the number * the check this library exists to stop people forgetting. The bounded wrapper
* of bytes written excluding the terminating NUL, and is 0 on any failure. * reports truncation instead.
*/ */
akerr_ErrorContext AKERR_NOIGNORE *aksl_vsnprintf(int *count, char *restrict str, size_t size, const char *restrict format, va_list args) akerr_ErrorContext AKERR_NOIGNORE *aksl_vsnprintf(char *restrict str, size_t size, const char *restrict format, va_list args)
{ {
int needed = 0; int needed = 0;
PREPARE_ERROR(e); PREPARE_ERROR(e);
FAIL_ZERO_RETURN(e, count, AKERR_NULLPOINTER, "count=%p, str=%p, format=%p", (void *)count, (void *)str, (void *)format); FAIL_ZERO_RETURN(e, str, AKERR_NULLPOINTER, "str=%p, format=%p", (void *)str, (void *)format);
*count = 0; FAIL_ZERO_RETURN(e, format, AKERR_NULLPOINTER, "str=%p, format=%p", (void *)str, (void *)format);
FAIL_ZERO_RETURN(e, str, AKERR_NULLPOINTER, "count=%p, str=%p, format=%p", (void *)count, (void *)str, (void *)format);
FAIL_ZERO_RETURN(e, format, AKERR_NULLPOINTER, "count=%p, str=%p, format=%p", (void *)count, (void *)str, (void *)format);
FAIL_ZERO_RETURN(e, size, AKERR_VALUE, "size=0 leaves no room even for the terminating NUL"); FAIL_ZERO_RETURN(e, size, AKERR_VALUE, "size=0 leaves no room even for the terminating NUL");
errno = 0; errno = 0;
needed = vsnprintf(str, size, format, args); needed = vsnprintf(str, size, format, args);
FAIL_NONZERO_RETURN(e, (needed < 0), AKSL_ERRNO_OR(AKERR_IO), "Output error"); FAIL_NONZERO_RETURN(e, (needed < 0), AKSL_ERRNO_OR(AKERR_IO), "Output error");
FAIL_NONZERO_RETURN(e, ((size_t)needed >= size), AKERR_OUTOFBOUNDS, FAIL_NONZERO_RETURN(e, ((size_t)needed >= size), AKERR_OUTOFBOUNDS,
"output truncated: %d bytes needed, %zu available", needed, size); "output truncated: %d bytes needed, %zu available", needed, size);
*count = needed;
SUCCEED_RETURN(e); SUCCEED_RETURN(e);
} }
akerr_ErrorContext AKERR_NOIGNORE *aksl_snprintf(int *count, char *restrict str, size_t size, const char *restrict format, ...) akerr_ErrorContext AKERR_NOIGNORE *aksl_snprintf(char *restrict str, size_t size, const char *restrict format, ...)
{ {
va_list args; va_list args;
akerr_ErrorContext *raised = NULL; akerr_ErrorContext *raised = NULL;
va_start(args, format); va_start(args, format);
raised = aksl_vsnprintf(count, str, size, format, args); raised = aksl_vsnprintf(str, size, format, args);
va_end(args); va_end(args);
return raised; return raised;
} }

3
tests/negative/format_mismatch.c
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@@ -16,11 +16,10 @@
int main(void) int main(void)
{ {
char buf[64]; char buf[64];
int count = 0;
akerr_ErrorContext *raised = NULL; akerr_ErrorContext *raised = NULL;
/* %d against a string. This is the line that must not build. */ /* %d against a string. This is the line that must not build. */
raised = aksl_snprintf(&count, buf, sizeof(buf), "%d", "not an int"); raised = aksl_snprintf(buf, sizeof(buf), "%d", "not an int");
return raised == NULL ? 0 : 1; return raised == NULL ? 0 : 1;
} }

59
tests/test_format.c
View File

@@ -2,10 +2,8 @@
* Formatted-output wrappers: aksl_printf / aksl_fprintf / aksl_snprintf and * Formatted-output wrappers: aksl_printf / aksl_fprintf / aksl_snprintf and
* their va_list forms. * their va_list forms.
* *
* Formatted output, complete. Each happy path asserts both halves of the * Formatted output, complete. Each happy path asserts the text that actually
* contract -- the byte count handed back through *count and the text that * landed somewhere, and every pointer argument is checked for its NULL guard.
* actually landed somewhere -- and every pointer argument is checked for its
* NULL guard.
* *
* Readback goes through plain libc rather than aksl_fread so that a failure here * Readback goes through plain libc rather than aksl_fread so that a failure here
* points at the formatted-output wrapper under test and not at the stream * points at the formatted-output wrapper under test and not at the stream
@@ -39,14 +37,12 @@ static long read_file(const char *path, char *buf, size_t n)
return (long)got; return (long)got;
} }
static int test_snprintf_writes_text_and_count(void) static int test_snprintf_writes_text(void)
{ {
char buf[64]; char buf[64];
int count = -1;
memset(buf, 0x00, sizeof(buf)); memset(buf, 0x00, sizeof(buf));
AKSL_CHECK_OK(aksl_snprintf(&count, buf, sizeof(buf), "%s=%d", "x", 7)); AKSL_CHECK_OK(aksl_snprintf(buf, sizeof(buf), "%s=%d", "x", 7));
AKSL_CHECK(count == 3);
AKSL_CHECK(strcmp(buf, "x=7") == 0); AKSL_CHECK(strcmp(buf, "x=7") == 0);
return 0; return 0;
} }
@@ -54,10 +50,8 @@ static int test_snprintf_writes_text_and_count(void)
static int test_snprintf_empty_format_writes_nothing(void) static int test_snprintf_empty_format_writes_nothing(void)
{ {
char buf[8] = { 'z', 'z', 'z', 'z', 'z', 'z', 'z', 'z' }; char buf[8] = { 'z', 'z', 'z', 'z', 'z', 'z', 'z', 'z' };
int count = -1;
AKSL_CHECK_OK(aksl_snprintf(&count, buf, sizeof(buf), "%s", "")); AKSL_CHECK_OK(aksl_snprintf(buf, sizeof(buf), "%s", ""));
AKSL_CHECK(count == 0);
AKSL_CHECK(buf[0] == '\0'); AKSL_CHECK(buf[0] == '\0');
return 0; return 0;
} }
@@ -66,18 +60,17 @@ static int test_snprintf_empty_format_writes_nothing(void)
* The case that could not be written while the wrapper was aksl_sprintf: output * The case that could not be written while the wrapper was aksl_sprintf: output
* longer than the destination. snprintf(3) would truncate, NUL-terminate and * longer than the destination. snprintf(3) would truncate, NUL-terminate and
* report the length it *would* have written, leaving the caller to notice; here * report the length it *would* have written, leaving the caller to notice; here
* it is an error, and *count is 0 rather than the would-have-been length. * it is an error.
*/ */
static int test_snprintf_truncation_is_an_error(void) static int test_snprintf_truncation_is_an_error(void)
{ {
char buf[8]; char buf[8];
int count = -1;
memset(buf, 0x00, sizeof(buf)); memset(buf, 0x00, sizeof(buf));
AKSL_CHECK_STATUS_MSG_CONTAINS( AKSL_CHECK_STATUS_MSG_CONTAINS(
aksl_snprintf(&count, buf, sizeof(buf), "%s", "far too long for eight bytes"), aksl_snprintf(buf, sizeof(buf), "%s", "far too long for eight bytes"),
AKERR_OUTOFBOUNDS, "truncated"); AKERR_OUTOFBOUNDS, "truncated");
AKSL_CHECK(count == 0); AKSL_CHECK(strcmp(buf, "far too") == 0);
return 0; return 0;
} }
@@ -85,34 +78,27 @@ static int test_snprintf_truncation_is_an_error(void)
static int test_snprintf_boundary_is_exact(void) static int test_snprintf_boundary_is_exact(void)
{ {
char buf[8]; char buf[8];
int count = -1;
/* 7 characters plus the NUL is exactly sizeof(buf). */ /* 7 characters plus the NUL is exactly sizeof(buf). */
AKSL_CHECK_OK(aksl_snprintf(&count, buf, sizeof(buf), "%s", "1234567")); AKSL_CHECK_OK(aksl_snprintf(buf, sizeof(buf), "%s", "1234567"));
AKSL_CHECK(count == 7);
AKSL_CHECK(strcmp(buf, "1234567") == 0); AKSL_CHECK(strcmp(buf, "1234567") == 0);
count = -1; AKSL_CHECK_STATUS(aksl_snprintf(buf, sizeof(buf), "%s", "12345678"),
AKSL_CHECK_STATUS(aksl_snprintf(&count, buf, sizeof(buf), "%s", "12345678"),
AKERR_OUTOFBOUNDS); AKERR_OUTOFBOUNDS);
AKSL_CHECK(count == 0);
return 0; return 0;
} }
static int test_snprintf_rejects_null_arguments_and_zero_size(void) static int test_snprintf_rejects_null_arguments_and_zero_size(void)
{ {
char buf[8]; char buf[8];
int count = 0;
memset(buf, 0x00, sizeof(buf)); memset(buf, 0x00, sizeof(buf));
AKSL_CHECK_STATUS_MSG_CONTAINS(aksl_snprintf(NULL, buf, sizeof(buf), "x"), AKSL_CHECK_STATUS_MSG_CONTAINS(aksl_snprintf(NULL, 8, "x"),
AKERR_NULLPOINTER, "count=");
AKSL_CHECK_STATUS_MSG_CONTAINS(aksl_snprintf(&count, NULL, 8, "x"),
AKERR_NULLPOINTER, "str="); AKERR_NULLPOINTER, "str=");
AKSL_CHECK_STATUS_MSG_CONTAINS(aksl_snprintf(&count, buf, sizeof(buf), NULL), AKSL_CHECK_STATUS_MSG_CONTAINS(aksl_snprintf(buf, sizeof(buf), NULL),
AKERR_NULLPOINTER, "format="); AKERR_NULLPOINTER, "format=");
/* size 0 leaves no room even for the terminator, so there is nothing to do. */ /* size 0 leaves no room even for the terminator, so there is nothing to do. */
AKSL_CHECK_STATUS_MSG_CONTAINS(aksl_snprintf(&count, buf, 0, "x"), AKSL_CHECK_STATUS_MSG_CONTAINS(aksl_snprintf(buf, 0, "x"),
AKERR_VALUE, "size=0"); AKERR_VALUE, "size=0");
return 0; return 0;
} }
@@ -274,14 +260,14 @@ static int test_asprintf_allocates_to_fit(void)
* wanted them exposed so consumers can write their own variadic wrappers. This * wanted them exposed so consumers can write their own variadic wrappers. This
* is a consumer doing exactly that. * is a consumer doing exactly that.
*/ */
static akerr_ErrorContext AKERR_NOIGNORE *consumer_wrapper(int *count, char *buf, size_t n, static akerr_ErrorContext AKERR_NOIGNORE *consumer_wrapper(char *buf, size_t n,
const char *fmt, ...) const char *fmt, ...)
{ {
va_list args; va_list args;
akerr_ErrorContext *raised = NULL; akerr_ErrorContext *raised = NULL;
va_start(args, fmt); va_start(args, fmt);
raised = aksl_vsnprintf(count, buf, n, fmt, args); raised = aksl_vsnprintf(buf, n, fmt, args);
va_end(args); va_end(args);
return raised; return raised;
} }
@@ -289,17 +275,14 @@ static akerr_ErrorContext AKERR_NOIGNORE *consumer_wrapper(int *count, char *buf
static int test_va_list_forms_are_usable_from_outside(void) static int test_va_list_forms_are_usable_from_outside(void)
{ {
char buf[32]; char buf[32];
int count = -1;
memset(buf, 0x00, sizeof(buf)); memset(buf, 0x00, sizeof(buf));
AKSL_CHECK_OK(consumer_wrapper(&count, buf, sizeof(buf), "%s/%d", "via", 3)); AKSL_CHECK_OK(consumer_wrapper(buf, sizeof(buf), "%s/%d", "via", 3));
AKSL_CHECK(count == 5);
AKSL_CHECK(strcmp(buf, "via/3") == 0); AKSL_CHECK(strcmp(buf, "via/3") == 0);
/* The error contract survives the extra layer intact. */ /* The error contract survives the extra layer intact. */
AKSL_CHECK_STATUS(consumer_wrapper(&count, buf, 4, "%s", "too long"), AKSL_CHECK_STATUS(consumer_wrapper(buf, 4, "%s", "too long"),
AKERR_OUTOFBOUNDS); AKERR_OUTOFBOUNDS);
AKSL_CHECK(count == 0);
return 0; return 0;
} }
@@ -312,14 +295,12 @@ static int test_va_list_forms_are_usable_from_outside(void)
static int test_variadic_wrappers_survive_repeated_calls(void) static int test_variadic_wrappers_survive_repeated_calls(void)
{ {
char buf[128]; char buf[128];
int count = 0;
int i = 0; int i = 0;
for ( i = 0; i < 512; i++ ) { for ( i = 0; i < 512; i++ ) {
AKSL_CHECK_OK(aksl_snprintf(&count, buf, sizeof(buf), "%d %s %ld %c %f", AKSL_CHECK_OK(aksl_snprintf(buf, sizeof(buf), "%d %s %ld %c %f",
i, "iteration", (long)i, 'x', (double)i)); i, "iteration", (long)i, 'x', (double)i));
AKSL_CHECK(count > 0); AKSL_CHECK(strlen(buf) > 0);
AKSL_CHECK((size_t)count == strlen(buf));
} }
return 0; return 0;
} }
@@ -330,7 +311,7 @@ int main(void)
akerr_init(); akerr_init();
AKSL_RUN(failures, test_snprintf_writes_text_and_count); AKSL_RUN(failures, test_snprintf_writes_text);
AKSL_RUN(failures, test_snprintf_empty_format_writes_nothing); AKSL_RUN(failures, test_snprintf_empty_format_writes_nothing);
AKSL_RUN(failures, test_snprintf_truncation_is_an_error); AKSL_RUN(failures, test_snprintf_truncation_is_an_error);
AKSL_RUN(failures, test_snprintf_boundary_is_exact); AKSL_RUN(failures, test_snprintf_boundary_is_exact);

8
tests/test_pool.c
View File

@@ -109,14 +109,13 @@ static int test_stream_wrappers_do_not_leak_slots(void)
static int test_format_wrappers_do_not_leak_slots(void) static int test_format_wrappers_do_not_leak_slots(void)
{ {
char buf[16]; char buf[16];
int count = 0;
int i = 0; int i = 0;
for ( i = 0; i < ROUNDS; i++ ) { for ( i = 0; i < ROUNDS; i++ ) {
AKSL_CHECK_STATUS(aksl_printf(NULL, "x"), AKERR_NULLPOINTER); AKSL_CHECK_STATUS(aksl_printf(NULL, "x"), AKERR_NULLPOINTER);
AKSL_CHECK_STATUS(aksl_fprintf(NULL, stdout, "x"), AKERR_NULLPOINTER); AKSL_CHECK_STATUS(aksl_fprintf(NULL, stdout, "x"), AKERR_NULLPOINTER);
AKSL_CHECK_STATUS(aksl_snprintf(NULL, buf, sizeof(buf), "x"), AKERR_NULLPOINTER); AKSL_CHECK_OK(aksl_snprintf(buf, sizeof(buf), "x"));
AKSL_CHECK_STATUS(aksl_snprintf(&count, buf, 4, "%s", "far too long"), AKSL_CHECK_STATUS(aksl_snprintf(buf, 4, "%s", "far too long"),
AKERR_OUTOFBOUNDS); AKERR_OUTOFBOUNDS);
AKSL_CHECK(aksl_slots_in_use() == 0); AKSL_CHECK(aksl_slots_in_use() == 0);
} }
@@ -266,7 +265,6 @@ static int test_traversal_failures_do_not_leak_slots(void)
static int test_errors_name_their_origin_in_stdlib(void) static int test_errors_name_their_origin_in_stdlib(void)
{ {
void *ptr = NULL; void *ptr = NULL;
int count = 0;
char resolved[PATH_MAX]; char resolved[PATH_MAX];
uint32_t h = 0; uint32_t h = 0;
aksl_ListNode node; aksl_ListNode node;
@@ -295,7 +293,7 @@ static int test_errors_name_their_origin_in_stdlib(void)
AKSL_CHECK_STATUS(aksl_printf(NULL, "x"), AKERR_NULLPOINTER); AKSL_CHECK_STATUS(aksl_printf(NULL, "x"), AKERR_NULLPOINTER);
AKSL_CHECK(came_from("aksl_vprintf", "src/stdlib.c") == 0); AKSL_CHECK(came_from("aksl_vprintf", "src/stdlib.c") == 0);
AKSL_CHECK_STATUS(aksl_snprintf(&count, NULL, 8, "x"), AKERR_NULLPOINTER); AKSL_CHECK_STATUS(aksl_snprintf(NULL, 8, "x"), AKERR_NULLPOINTER);
AKSL_CHECK(came_from("aksl_vsnprintf", "src/stdlib.c") == 0); AKSL_CHECK(came_from("aksl_vsnprintf", "src/stdlib.c") == 0);
/* Likewise, the ato* forms are calls into the strto* ones. */ /* Likewise, the ato* forms are calls into the strto* ones. */