1f010d6bdf
We presently use the ".txt" extension for our AsciiDoc files. While not wrong, most editors do not associate this extension with AsciiDoc, meaning that contributors don't get automatic editor functionality that could be useful, such as syntax highlighting and prose linting. It is much more common to use the ".adoc" extension for AsciiDoc files, since this helps editors automatically detect files and also allows various forges to provide rich (HTML-like) rendering. Let's do that here, renaming all of the files and updating the includes where relevant. Adjust the various build scripts and makefiles to use the new extension as well. Note that this should not result in any user-visible changes to the documentation. Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net> Signed-off-by: Junio C Hamano <gitster@pobox.com>
104 lines
3.7 KiB
Plaintext
104 lines
3.7 KiB
Plaintext
Error reporting in git
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======================
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`BUG`, `bug`, `die`, `usage`, `error`, and `warning` report errors of
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various kinds.
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- `BUG` is for failed internal assertions that should never happen,
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i.e. a bug in git itself.
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- `bug` (lower-case, not `BUG`) is supposed to be used like `BUG` but
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prints a "BUG" message instead of calling `abort()`.
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+
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A call to `bug()` will then result in a "real" call to the `BUG()`
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function, either explicitly by invoking `BUG_if_bug()` after call(s)
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to `bug()`, or implicitly at `exit()` time where we'll check if we
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encountered any outstanding `bug()` invocations.
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+
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If there were no prior calls to `bug()` before invoking `BUG_if_bug()`
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the latter is a NOOP. The `BUG_if_bug()` function takes the same
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arguments as `BUG()` itself. Calling `BUG_if_bug()` explicitly isn't
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necessary, but ensures that we die as soon as possible.
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+
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If you know you had prior calls to `bug()` then calling `BUG()` itself
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is equivalent to calling `BUG_if_bug()`, the latter being a wrapper
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calling `BUG()` if we've set a flag indicating that we've called
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`bug()`.
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+
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This is for the convenience of APIs who'd like to potentially report
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more than one "bug", such as the optbug() validation in
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parse-options.c.
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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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These reports will be logged via the trace2 facility. See the "error"
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event in link:api-trace2.html[trace2 API].
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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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