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selftests/powerpc: Parse long/unsigned long value safely

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Often a file is expected to hold an integral value. Existing functions
will use a C stdlib function like atoi or strtol to parse the file.
These operations are error prone, with complicated error conditions
(atoi returns 0 if not a number, and is undefined behaviour if not in
range. strtol returns 0 if not a number, and LONG_MIN/MAX if not in
range + sets errno to ERANGE).

Signed-off-by: Benjamin Gray <bgray@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20230203003947.38033-4-bgray@linux.ibm.com
This commit is contained in:
Benjamin Gray 2023-02-03 11:39:45 +11:00 committed by Michael Ellerman
parent 121d340be9
commit d1bc05b7bf
3 changed files with 132 additions and 7 deletions
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7
tools/testing/selftests/powerpc/include/utils.h
View File

@ -33,6 +33,13 @@ void *get_auxv_entry(int type);
int pick_online_cpu(void);
int parse_intmax(const char *buffer, size_t count, intmax_t *result, int base);
int parse_uintmax(const char *buffer, size_t count, uintmax_t *result, int base);
int parse_int(const char *buffer, size_t count, int *result, int base);
int parse_uint(const char *buffer, size_t count, unsigned int *result, int base);
int parse_long(const char *buffer, size_t count, long *result, int base);
int parse_ulong(const char *buffer, size_t count, unsigned long *result, int base);
int read_file(const char *path, char *buf, size_t count, size_t *len);
int write_file(const char *path, const char *buf, size_t count);
int read_debugfs_file(const char *debugfs_file, char *buf, size_t count);

6
tools/testing/selftests/powerpc/pmu/lib.c
View File

@ -192,7 +192,6 @@ bool require_paranoia_below(int level)
{
int err;
long current;
char *end;
char buf[16] = {0};
err = read_file(PARANOID_PATH, buf, sizeof(buf) - 1, NULL);
@ -201,9 +200,8 @@ bool require_paranoia_below(int level)
return false;
}
current = strtol(buf, &end, 10);
if (end == buf) {
err = parse_long(buf, sizeof(buf), &current, 10);
if (err) {
printf("Couldn't parse " PARANOID_PATH "?\n");
return false;
}

126
tools/testing/selftests/powerpc/utils.c
View File

@ -8,6 +8,8 @@
#include <elf.h>
#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <limits.h>
#include <link.h>
#include <sched.h>
#include <stdio.h>
@ -123,6 +125,126 @@ int write_debugfs_file(const char *subpath, const char *buf, size_t count)
return write_file(path, buf, count);
}
static int validate_int_parse(const char *buffer, size_t count, char *end)
{
int err = 0;
/* Require at least one digit */
if (end == buffer) {
err = -EINVAL;
goto out;
}
/* Require all remaining characters be whitespace-ish */
for (; end < buffer + count; end++) {
if (*end == '\0')
break;
if (*end != ' ' && *end != '\n') {
err = -EINVAL;
goto out;
}
}
out:
errno = -err;
return err;
}
static int parse_bounded_int(const char *buffer, size_t count, intmax_t *result,
int base, intmax_t min, intmax_t max)
{
int err;
char *end;
errno = 0;
*result = strtoimax(buffer, &end, base);
if (errno)
return -errno;
err = validate_int_parse(buffer, count, end);
if (err)
goto out;
if (*result < min || *result > max)
err = -EOVERFLOW;
out:
errno = -err;
return err;
}
static int parse_bounded_uint(const char *buffer, size_t count, uintmax_t *result,
int base, uintmax_t max)
{
int err = 0;
char *end;
errno = 0;
*result = strtoumax(buffer, &end, base);
if (errno)
return -errno;
err = validate_int_parse(buffer, count, end);
if (err)
goto out;
if (*result > max)
err = -EOVERFLOW;
out:
errno = -err;
return err;
}
int parse_intmax(const char *buffer, size_t count, intmax_t *result, int base)
{
return parse_bounded_int(buffer, count, result, base, INTMAX_MIN, INTMAX_MAX);
}
int parse_uintmax(const char *buffer, size_t count, uintmax_t *result, int base)
{
return parse_bounded_uint(buffer, count, result, base, UINTMAX_MAX);
}
int parse_int(const char *buffer, size_t count, int *result, int base)
{
intmax_t parsed;
int err = parse_bounded_int(buffer, count, &parsed, base, INT_MIN, INT_MAX);
*result = parsed;
return err;
}
int parse_uint(const char *buffer, size_t count, unsigned int *result, int base)
{
uintmax_t parsed;
int err = parse_bounded_uint(buffer, count, &parsed, base, UINT_MAX);
*result = parsed;
return err;
}
int parse_long(const char *buffer, size_t count, long *result, int base)
{
intmax_t parsed;
int err = parse_bounded_int(buffer, count, &parsed, base, LONG_MIN, LONG_MAX);
*result = parsed;
return err;
}
int parse_ulong(const char *buffer, size_t count, unsigned long *result, int base)
{
uintmax_t parsed;
int err = parse_bounded_uint(buffer, count, &parsed, base, ULONG_MAX);
*result = parsed;
return err;
}
void *find_auxv_entry(int type, char *auxv)
{
ElfW(auxv_t) *p;
@ -224,9 +346,7 @@ int read_debugfs_int(const char *debugfs_file, int *result)
if (err)
return err;
*result = atoi(value);
return 0;
return parse_int(value, sizeof(value), result, 10);
}
int write_debugfs_int(const char *debugfs_file, int result)