git/diff-no-index.c, branch v2.50.1

hash: stop depending on `the_repository` in `null_oid()`

2025-03-10T20:16:20Z

The `null_oid()` function returns the object ID that only consists of zeroes. Naturally, this ID also depends on the hash algorithm used, as the number of zeroes is different between SHA1 and SHA256. Consequently, the function returns the hash-algorithm-specific null object ID. This is currently done by depending on `the_hash_algo`, which implicitly makes us depend on `the_repository`. Refactor the function to instead pass in the hash algorithm for which we want to retrieve the null object ID. Adapt callsites accordingly by passing in `the_repository`, thus bubbling up the dependency on that global variable by one layer. There are a couple of trivial exceptions for subsystems that already got rid of `the_repository`. These subsystems instead use the repository that is available via the calling context: - "builtin/grep.c" - "grep.c" - "refs/debug.c" There are also two non-trivial exceptions: - "diff-no-index.c": Here we know that we may not have a repository initialized at all, so we cannot rely on `the_repository`. Instead, we adapt `diff_no_index()` to get a `struct git_hash_algo` as parameter. The only caller is located in "builtin/diff.c", where we know to call `repo_set_hash_algo()` in case we're running outside of a Git repository. Consequently, it is fine to continue passing `the_repository->hash_algo` even in this case. - "builtin/ls-files.c": There is an in-flight patch series that drops `USE_THE_REPOSITORY_VARIABLE` in this file, which causes a semantic conflict because we use `null_oid()` in `show_submodule()`. The value is passed to `repo_submodule_init()`, which may use the object ID to resolve a tree-ish in the superproject from which we want to read the submodule config. As such, the object ID should refer to an object in the superproject, and consequently we need to use its hash algorithm. This means that we could in theory just not bother about this edge case at all and just use `the_repository` in "diff-no-index.c". But doing so would feel misdesigned. Remove the `USE_THE_REPOSITORY_VARIABLE` preprocessor define in "hash.c". Signed-off-by: Patrick Steinhardt Signed-off-by: Junio C Hamano

global: mark code units that generate warnings with `-Wsign-compare`

2024-12-06T11:20:02Z

Mark code units that generate warnings with `-Wsign-compare`. This allows for a structured approach to get rid of all such warnings over time in a way that can be easily measured. Signed-off-by: Patrick Steinhardt Signed-off-by: Junio C Hamano

remerge-diff: clean up temporary objdir at a central place

2024-08-09T22:42:40Z

After running a diff between two things, or a series of diffs while walking the history, the diff computation is concluded by a call to diff_result_code() to extract the exit status of the diff machinery. The function can work on "struct diffopt", but all the callers historically and currently pass "struct diffopt" that is embedded in the "struct rev_info" that is used to hold the remerge_diff bit and the remerge_objdir variable that points at the temporary object directory in use. Redefine diff_result_code() to take the whole "struct rev_info" to give it an access to these members related to remerge-diff, so that it can get rid of the temporary object directory for any and all callers that used the feature. We can lose the equivalent code to do so from the code paths for individual commands, diff-tree, diff, and log. Signed-off-by: Junio C Hamano

treewide: remove unnecessary includes in source files

2023-12-26T20:04:31Z

Each of these were checked with gcc -E -I. ${SOURCE_FILE} | grep ${HEADER_FILE} to ensure that removing the direct inclusion of the header actually resulted in that header no longer being included at all (i.e. that no other header pulled it in transitively). ...except for a few cases where we verified that although the header was brought in transitively, nothing from it was directly used in that source file. These cases were: * builtin/credential-cache.c * builtin/pull.c * builtin/send-pack.c Signed-off-by: Elijah Newren Signed-off-by: Junio C Hamano

Merge branch 'pw/diff-no-index-from-named-pipes'

2023-09-20T17:44:57Z

"git diff --no-index -R <(one) <(two)" did not work correctly, which has been corrected. * pw/diff-no-index-from-named-pipes: diff --no-index: fix -R with stdin

diff --no-index: fix -R with stdin

2023-09-11T19:05:37Z

When -R is given, queue_diff() swaps the mode and name variables of the two files to produce a reverse diff. 1e3f26542a (diff --no-index: support reading from named pipes, 2023-07-05) added variables that indicate whether files are special, i.e named pipes or - for stdin. These new variables were not swapped, though, which broke the handling of stdin with with -R. Swap them like the other metadata variables. Reported-by: Martin Storsjö Signed-off-by: René Scharfe Signed-off-by: Junio C Hamano

diff: drop useless "status" parameter from diff_result_code()

2023-08-21T22:33:24Z

Many programs use diff_result_code() to get a user-visible program exit code from a diff result (e.g., checking opts.found_changes if --exit-code was requested). This function also takes a "status" parameter, which seems at first glance that it could be used to propagate an error encountered when computing the diff. But it doesn't work that way: - negative values are passed through as-is, but are not appropriate as program exit codes - when --exit-code or --check is in effect, we _ignore_ the passed-in status completely. So a failed diff which did not have a chance to set opts.found_changes would erroneously report "success, no changes" instead of propagating the error. After recent cleanups, neither of these bugs is possible to trigger, as every caller just passes in "0". So rather than fixing them, we can simply drop the useless parameter instead. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano

diff --no-index: support reading from named pipes

2023-07-05T21:00:28Z

In some shells, such as bash and zsh, it's possible to use a command substitution to provide the output of a command as a file argument to another process, like so: diff -u <(printf "a\nb\n") <(printf "a\nc\n") However, this syntax does not produce useful results with "git diff --no-index". On macOS, the arguments to the command are named pipes under /dev/fd, and git diff doesn't know how to handle a named pipe. On Linux, the arguments are symlinks to pipes, so git diff "helpfully" diffs these symlinks, comparing their targets like "pipe:[1234]" and "pipe:[5678]". To address this "diff --no-index" is changed so that if a path given on the commandline is a named pipe or a symbolic link that resolves to a named pipe then we read the data to diff from that pipe. This is implemented by generalizing the code that already exists to handle reading from stdin when the user passes the path "-". If the user tries to compare a named pipe to a directory then we die as we do when trying to compare stdin to a directory. As process substitution is not support by POSIX this change is tested by using a pipe and a symbolic link to a pipe. Helped-by: Junio C Hamano Signed-off-by: Phillip Wood Signed-off-by: Junio C Hamano

diff --no-index: die on error reading stdin

2023-07-05T21:00:28Z

If there is an error when reading from stdin then "diff --no-index" prints an error message but continues to try and diff a file named "-" resulting in an error message that looks like error: error while reading from stdin: Invalid argument fatal: stat '-': No such file or directory assuming that no file named "-" exists. If such a file exists it prints the first error message and generates the diff from that file which is not what the user wanted. Instead just die() straight away if we cannot read from stdin. Signed-off-by: Phillip Wood Signed-off-by: Junio C Hamano

diff --no-index: refuse to compare stdin to a directory

2023-07-05T21:00:28Z

When the user runs git diff --no-index file directory we follow the behavior of POSIX diff and rewrite the arguments as git diff --no-index file directory/file Doing that when "file" is "-" (which means "read from stdin") does not make sense so we should error out if the user asks us to compare "-" to a directory. This matches the behavior of GNU diff and diff on *BSD. Signed-off-by: Phillip Wood Signed-off-by: Junio C Hamano