39d5bef5c1
Signed-off-by: Thomas Ackermann <th.acker@arcor.de> Signed-off-by: Junio C Hamano <gitster@pobox.com>
76 lines
2.5 KiB
Plaintext
76 lines
2.5 KiB
Plaintext
Error reporting in git
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======================
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`die`, `usage`, `error`, and `warning` report errors of various
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kinds.
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- `die` is for fatal application errors. It prints a message to
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the user and exits with status 128.
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- `usage` is for errors in command line usage. After printing its
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message, it exits with status 129. (See also `usage_with_options`
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in the link:api-parse-options.html[parse-options API].)
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- `error` is for non-fatal library errors. It prints a message
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to the user and returns -1 for convenience in signaling the error
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to the caller.
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- `warning` is for reporting situations that probably should not
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occur but which the user (and Git) can continue to work around
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without running into too many problems. Like `error`, it
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returns -1 after reporting the situation to the caller.
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Customizable error handlers
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---------------------------
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The default behavior of `die` and `error` is to write a message to
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stderr and then exit or return as appropriate. This behavior can be
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overridden using `set_die_routine` and `set_error_routine`. For
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example, "git daemon" uses set_die_routine to write the reason `die`
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was called to syslog before exiting.
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Library errors
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--------------
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Functions return a negative integer on error. Details beyond that
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vary from function to function:
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- Some functions return -1 for all errors. Others return a more
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specific value depending on how the caller might want to react
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to the error.
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- Some functions report the error to stderr with `error`,
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while others leave that for the caller to do.
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- errno is not meaningful on return from most functions (except
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for thin wrappers for system calls).
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Check the function's API documentation to be sure.
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Caller-handled errors
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---------------------
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An increasing number of functions take a parameter 'struct strbuf *err'.
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On error, such functions append a message about what went wrong to the
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'err' strbuf. The message is meant to be complete enough to be passed
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to `die` or `error` as-is. For example:
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if (ref_transaction_commit(transaction, &err))
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die("%s", err.buf);
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The 'err' parameter will be untouched if no error occurred, so multiple
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function calls can be chained:
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t = ref_transaction_begin(&err);
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if (!t ||
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ref_transaction_update(t, "HEAD", ..., &err) ||
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ret_transaction_commit(t, &err))
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die("%s", err.buf);
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The 'err' parameter must be a pointer to a valid strbuf. To silence
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a message, pass a strbuf that is explicitly ignored:
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if (thing_that_can_fail_in_an_ignorable_way(..., &err))
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/* This failure is okay. */
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strbuf_reset(&err);
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