Simplify error handling (mainly, error messages) #1314
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The double parentheses were used to fake a variadic macro with a non-variadic one. With a variadic macro, we remove the weird double parentheses that were needed to call this macro, which BTW were error-prone. This would have prevented the bug fixed in 3f5ae5d (2025-09-10; "src/su.c: Fix incorrect (non-matching) parentheses"). Signed-off-by: Alejandro Colomar <alx@kernel.org>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
The name of this macro makes it more evident what it does. It's a C-locale version of syslog(3). We need to implement it as a macro so that arguments such as strerror(3) are evaluated after setting the C locale. This would be impossible with a function. Signed-off-by: Alejandro Colomar <alx@kernel.org>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
There's no need for two variables, and this avoids one assignment. Signed-off-by: Alejandro Colomar <alx@kernel.org>
…nally Both setlocale(3) and free(3) are okay to call with a null pointer. Signed-off-by: Alejandro Colomar <alx@kernel.org>
In some cases, we print strerrno() with this macro. Because this is a macro, and internal calls such as strdup(3) may set errno, that value could be corrupted when we arrive at syslog(3). While we could solve this here, it's not robust. Instead, we'll use a dedicated wrapper for that, which will be added in the following commits: SYSLOGE(). What we'll do here is preserve errno when we exit from this macro, as we often follow SYSLOG() calls with fprintf(stderr,) calls, which also use the errno value, and we don't want to pollute that. Signed-off-by: Alejandro Colomar <alx@kernel.org>
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Signed-off-by: Alejandro Colomar <alx@kernel.org>
These functions print a formatted string, followed by a colon and a space, followed by an error string produced by strerror($2). That is, the output is as follows: fmt: error message string For example, fprintec(stderr, ENOMEM, "foo(%d)", 42); prints foo(42): Cannot allocate memory These functions return the number of characters printed, or a negative value on error, like fprintf(3). Signed-off-by: Alejandro Colomar <alx@kernel.org>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
fprinte() is like fprintec(), but uses errno instead of an error code. It is implemented as a macro so that it can read the value in errno before evaluating any of its arguments, thus not corrupting it. It also preserves errno so that the error can be printed more than once. This is useful because we often print to stderr or log_get_logfd(), and immediately after print to the system log with syslog(3). Signed-off-by: Alejandro Colomar <alx@kernel.org>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
like the fprintf(3) wrappers, these print an error message. SYSLOGE() uses errno, and SYSLOGEC() uses an errno-like error code. This time we need to be careful to name the local copy of errno differently than within SYSLOG() --which we call--. Let's use a double underscore. In the future, C might have function literals (similar to lambdas), which will solve this issue. Signed-off-by: Alejandro Colomar <alx@kernel.org>
Having such long and complex format strings and variadic arguments is error-prone, as can be seen in the previous commit, which fixes a bug of this kind. Signed-off-by: Alejandro Colomar <alx@kernel.org>
This will allow having shorter lines for writing to stderr. This name is commonly used in other projects, it seems (see link below). Link: <https://gcc.gnu.org/onlinedocs/gcc-3.1.1/cpp/Variadic-Macros.html> Signed-off-by: Alejandro Colomar <alx@kernel.org>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
Print simpler messages that don't need translation. Check libc errors with ==-1 and ==NULL instead of <0 (or !=0) and !p. Signed-off-by: Alejandro Colomar <alx@kernel.org>
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Queued after #1289 .