diff options
Diffstat (limited to 'include/osmocom/core/utils.h')
| -rw-r--r-- | include/osmocom/core/utils.h | 56 |
1 files changed, 56 insertions, 0 deletions
diff --git a/include/osmocom/core/utils.h b/include/osmocom/core/utils.h index c4e6f5fc..86d45bcc 100644 --- a/include/osmocom/core/utils.h +++ b/include/osmocom/core/utils.h @@ -3,6 +3,7 @@ #include <stdbool.h> #include <stdint.h> #include <stdio.h> +#include <string.h> #include <osmocom/core/backtrace.h> #include <osmocom/core/talloc.h> @@ -271,4 +272,59 @@ struct osmo_strbuf { bool osmo_str_startswith(const char *str, const char *startswith_str); +/*! Translate a buffer function to a talloc context function. + * This is the full function body of a char *foo_name_c(void *ctx, val...) function, implemented by an + * int foo_name_buf(buf, buflen, val...) function: + * + * char *foo_name_c(void *ctx, example_t arg) + * { + * OSMO_NAME_C_IMPL(ctx, 64, "ERROR", foo_name_buf, arg) + * } + * + * Return a talloc'd string containing the result of the given foo_name_buf() function, or ON_ERROR on error in the called + * foo_name_buf() function. + * + * If ON_ERROR is NULL, the function returns NULL on error rc from FUNC_BUF. Take care: returning NULL in printf() like + * formats (LOGP()) makes the program crash. If ON_ERROR is non-NULL, it must be a string constant, which is not + * returned directly, but written to an allocated string buffer first. + * + * \param[in] INITIAL_BUFSIZE Which size to first talloc from ctx -- a larger size makes a reallocation less likely, a + * smaller size allocates less unused bytes, zero allocates once but still runs the string composition twice. + * \param[in] ON_ERROR String constant to copy on error rc returned by FUNC_BUF, or NULL to return NULL. + * \param[in] FUNC_BUF Name of a function with signature foo_buf(char *buf, size_t buflen, ...). + * \param[in] FUNC_BUF_ARGS Additional arguments to pass to FUNC_BUF after the buf and buflen. + */ +#define OSMO_NAME_C_IMPL(CTX, INITIAL_BUFSIZE, ON_ERROR, FUNC_BUF, FUNC_BUF_ARGS...) \ + size_t _len = INITIAL_BUFSIZE; \ + int _needed; \ + char *_str = NULL; \ + if ((INITIAL_BUFSIZE) > 0) { \ + _str = (char*)talloc_named_const(CTX, _len, __func__); \ + OSMO_ASSERT(_str); \ + } \ + _needed = FUNC_BUF(_str, _len, ## FUNC_BUF_ARGS); \ + if (_needed < 0) \ + goto OSMO_NAME_C_on_error; \ + if (_needed < _len) \ + return _str; \ + _len = _needed + 1; \ + if (_str) \ + talloc_free(_str); \ + _str = (char*)talloc_named_const(CTX, _len, __func__); \ + OSMO_ASSERT(_str); \ + _needed = FUNC_BUF(_str, _len, ## FUNC_BUF_ARGS); \ + if (_needed < 0) \ + goto OSMO_NAME_C_on_error; \ + return _str; \ +OSMO_NAME_C_on_error: \ + /* Re-using and re-sizing above allocated buf ends up in very complex code. Just free and strdup. */ \ + if (_str) \ + talloc_free(_str); \ + if (!(ON_ERROR)) \ + return NULL; \ + _str = talloc_strdup(CTX, ON_ERROR); \ + OSMO_ASSERT(_str); \ + talloc_set_name_const(_str, __func__); \ + return _str; + /*! @} */ |