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| -rw-r--r-- | include/slibc-error.h | 233 | ||||
| -rw-r--r-- | src/slibc-error.c | 76 |
2 files changed, 309 insertions, 0 deletions
diff --git a/include/slibc-error.h b/include/slibc-error.h new file mode 100644 index 0000000..c84faad --- /dev/null +++ b/include/slibc-error.h @@ -0,0 +1,233 @@ +/** + * slibc — Yet another C library + * Copyright © 2015 Mattias Andrée (maandree@member.fsf.org) + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ +#ifndef _SLIBC_ERROR_H +#define _SLIBC_ERROR_H +#ifndef _PORTABLE_SOURCE +#include <slibc/version.h> + + +#include <slibc/features.h> +#include <stdarg.h> +#include <errno.h> + + + +/** + * Store the current line, so we know which line failed, when + * `PRINT_CUSTOM_FAILURE`, `PRINT_FAILURE` or `slibc_perror` + * is called. This expression will be evaluated. + * + * Example usage: + * ``` + * int my_function(void) + * { + * size_t n; + * void* array; + * ... + * if (FAILABLE_CALL(array = malloc(n)) == NULL) + * goto fail; + * ... + * return 0; + * + * fail: + * PRINT_FAILURE(NULL); + * ... + * return errno = 0, -1; + * } + * ``` + * + * A more scalable example: + * ``` + * #define fail_if (call_and_check) \ + * do { if (FAILABLE_CALL(call_and_check)) goto fail; } while (0) + * // `try` or simply `t` may be even better. + * + * #define fail_unless (call_and_check) fail_if(!(call_and_check)) + * // `f` may be even better. + * + * int my_function(void) + * { + * size_t n; + * void* array; + * ... + * fail_if (!(array = malloc(n))); + * // or perhaps, fail_unless (array = malloc(n)); + * ... + * return 0; + * + * fail: + * PRINT_FAILURE(NULL); + * ... + * return errno = 0, -1; + * } + * ``` + * + * This is a slibc extension. + */ +#define FAILABLE_CALL(expression) \ + ({ typeof(expression) __slibc_r = (expression); *__slibc_error_line() = __LINE__; __slibc_r; }) + +/** + * Check whether an error occurred. If an error occurred, + * stored the line, for `PRINT_CUSTOM_FAILURE`, `PRINT_FAILURE` + * or `slibc_perror`, where the error occurred. + * + * Example usage: + * ``` + * int my_function(void) + * { + * char* buf; + * size_t bufsize; + * ssize_t r; + * int fd; + * ... + * for (;;) + * { + * r = read(fd, buf, bufsize); + * if (FAILURE_CHECK(r < 0, 1)) + * { + * if (errno != EINTR) // Possibly FAILURE_CHECK(errno != EINTR, 3) here instead. + * goto fail; + * continue; + * } + * ... + * } + * ... + * return 0; + * + * fail: + * PRINT_FAILURE(NULL); + * ... + * return errno = 0, -1; + * } + * ``` + * + * This is a slibc extension. + * + * @param condition Should evaluate to non-zero on and only on error. + * @param offset The number of lines above the current line + * that was the line that failed, if `condition` + * evaluates to non-zero. + * @return 1 if `condition` evaluates to non-zero, 0 otherwise. + */ +#define FAILURE_CHECK(condition, offset) \ + ((condition) ? (*__slibc_error_line() = (__LINE__ - (offset)), 1) : 0) + +/** + * Print an error message describing the error, and where the error + * happened. Optionally with detailed description of the action that + * failed. + * + * This function must be called in the same file and function as the + * the expansion of `FAILABLE_CALL` or `FAILURE_CHECK`. It is recommended + * that this is done all the way down the call-stack to `main'. This is + * however problematic (although it is possible) if you do not want the + * process to exit. + * + * Example of recursion: + * ``` + * static int b(void) + * { + * if (FAILABLE_CALL(some_function()) < 0) goto fail; + * return 0; fail: PRINT_FAILURE(NULL); return -1; + * } + * static int a(void) + * { + * if (FAILABLE_CALL(b()) < 0) goto fail; + * return 0; fail: PRINT_FAILURE(NULL); return -1; + * } + * int main(void) + * { + * if (FAILABLE_CALL(a()) < 0) goto fail; + * return 0; fail: PRINT_FAILURE(NULL); return 1; + * } + * ``` + * + * This function will set `errno` to zero. If you have statements + * after the call to this function that may modify `errno`, be sure + * to set `errno` to zero before returning. A good way to do this + * is to have the return statement look like `return errno = 0, -1`. + * + * This is a slibc extension. + * + * @param ... Formatting-string followed by formatting-arguments used + * to describe what action failed. If the first argument is + * `NULL`, this is not printed and only the location of the + * error and `errno` is used to describe the error. + */ +#define PRINT_FAILURE(...) \ + (PRINT_CUSTOM_FAILURE(errno, NULL, __VA_ARGS__)) + +/** + * Variant of `PRINT_FAILURE` that allows another function than `strerror` + * to be used to get a textual description of the error code. + * (This function will not set `errno` to zero unless it is the first argument.) + * + * Example: `PRINT_CUSTOM_FAILURE(r, gai_strerror(r), _("fail to connect to server: %s"), host)` + * + * This is a slibc extension. + * + * @param error_code The error code, must be a modifiable lvalue, as it will be + * modified to zero to indicate that the error string has + * already been printed. Thus, on the original error location + * this value must not be zero. + * @param error_string Textual representation of the error. If `errno` indicates + * the error, this should usually be `strerror(errno)`. + * @param ... Formatting-string followed by formatting-arguments used + * to describe what action failed. If the first argument is + * `NULL`, this is not printed and only the location of the + * error and `error_string` is used to describe the error. + */ +#define PRINT_CUSTOM_FAILURE(error_code, error_string, ...) \ + (slibc_perror(NULL, __FILE__, *__slibc_error_line(), __func__, &(error_code), error_string, __VA_ARGS__)) + +/** + * Helper function to keep track of the line of origin, in a + * thread-safe manner, without requiring new revisions of C. + */ +int* __slibc_error_line(void) __GCC_ONLY(__attribute__((__const__))); /* TODO not implemented */ + +/** + * Print a description of an error, and where the error occurred. + * This function is capable of printed the full call-stack. + * + * It is not recommended to used this function direction. + * Use the macros in <slibc-error.h> instead. + * + * This is a slibc extension. + * + * @param progname The name of the program, `NULL` to use `program_invocation_name`. + * @param filename The source code file where the error occurred. + * @param linenum The line in the source code where the error occurred. + * @param function The function in the source code where the error occurred. + * @param error_code Pointer the variable that stores the error code, will zeroed. + * @param error_string Textual description of the error code, `NULL` if `strerror` should be used. + * This parameter is unused if `error_code` is zero. + * @param format Formatting-string for a description of the action that failed. `NULL` if + * no description other than the location and `error_string` should be printed. + * @param ... Formatting-arguments for `format`. + */ +void slibc_perror(const char* progname, const char* filename, int linenum, const char* function, + int* error_code, const char* error_string, const char* format, ...) + __GCC_ONLY(__attribute__((nonnull(2, 4), format(printf, 7, 8)))); + + + +#endif +#endif + diff --git a/src/slibc-error.c b/src/slibc-error.c new file mode 100644 index 0000000..0094235 --- /dev/null +++ b/src/slibc-error.c @@ -0,0 +1,76 @@ +/** + * slibc — Yet another C library + * Copyright © 2015 Mattias Andrée (maandree@member.fsf.org) + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see <http://www.gnu.org/licenses/>. + */ +#include <slibc-error.h> +#include <stdio.h> +#include <unistd.h> +#include <string.h> + + + +/** + * Print a description of an error, and where the error occurred. + * This function is capable of printed the full call-stack. + * + * It is not recommended to used this function direction. + * Use the macros in <slibc-error.h> instead. + * + * This is a slibc extension. + * + * @param progname The name of the program, `NULL` to use `program_invocation_name`. + * @param filename The source code file where the error occurred. + * @param linenum The line in the source code where the error occurred. + * @param function The function in the source code where the error occurred. + * @param error_code Pointer the variable that stores the error code, will zeroed. + * @param error_string Textual description of the error code, `NULL` if `strerror` should be used. + * This parameter is unused if `error_code` is zero. + * @param format Formatting-string for a description of the action that failed. `NULL` if + * no description other than the location and `error_string` should be printed. + * @param ... Formatting-arguments for `format`. + */ +void slibc_perror(const char* progname, const char* filename, int linenum, const char* function, + int* error_code, const char* error_string, const char* format, ...) +{ + int tty = isatty(STDERR_FILENO); + va_list args; + + if (progname == NULL) + progname = program_invocation_name; + + if (*error_code) + { + if (error_string == NULL) + error_string = strerror(*error_code); + fflush(stdout); + fprintf(stderr, "%(\033[0;1;31m%)%s%(\033[21m%): %s%(\033[0m%)\n", + tty, progname, tty, error_string, tty); + } + + fprintf(stderr, " at \033[1;34m%s\033[0m (\033[35m%s\033[0m:\033[32m%i\033[0m)", + function, filename, linenum); + if (format != NULL) + { + fprintf(stderr, "\n "); + va_start(args, format); + vfprintf(stderr, format, args); + va_end(args); + } + + fprintf(stderr, "\n"); + *error_code = 0; +} + |