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[jc: with quite a few fixups] Signed-off-by: Miklos Vajna <vmiklos@frugalware.org> Signed-off-by: Junio C Hamano <gitster@pobox.com>maint
Miklos Vajna
17 years ago
committed by
Junio C Hamano
4 changed files with 168 additions and 161 deletions
@ -0,0 +1,161 @@
@@ -0,0 +1,161 @@
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Generating patches with -p |
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-------------------------- |
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When "git-diff-index", "git-diff-tree", or "git-diff-files" are run |
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with a '-p' option, "git diff" without the '--raw' option, or |
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"git log" with the "-p" option, they |
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do not produce the output described above; instead they produce a |
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patch file. You can customize the creation of such patches via the |
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GIT_EXTERNAL_DIFF and the GIT_DIFF_OPTS environment variables. |
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What the -p option produces is slightly different from the traditional |
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diff format. |
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1. It is preceded with a "git diff" header, that looks like |
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this: |
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diff --git a/file1 b/file2 |
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+ |
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The `a/` and `b/` filenames are the same unless rename/copy is |
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involved. Especially, even for a creation or a deletion, |
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`/dev/null` is _not_ used in place of `a/` or `b/` filenames. |
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+ |
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When rename/copy is involved, `file1` and `file2` show the |
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name of the source file of the rename/copy and the name of |
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the file that rename/copy produces, respectively. |
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2. It is followed by one or more extended header lines: |
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old mode <mode> |
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new mode <mode> |
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deleted file mode <mode> |
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new file mode <mode> |
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copy from <path> |
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copy to <path> |
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rename from <path> |
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rename to <path> |
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similarity index <number> |
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dissimilarity index <number> |
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index <hash>..<hash> <mode> |
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3. TAB, LF, double quote and backslash characters in pathnames |
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are represented as `\t`, `\n`, `\"` and `\\`, respectively. |
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If there is need for such substitution then the whole |
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pathname is put in double quotes. |
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The similarity index is the percentage of unchanged lines, and |
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the dissimilarity index is the percentage of changed lines. It |
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is a rounded down integer, followed by a percent sign. The |
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similarity index value of 100% is thus reserved for two equal |
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files, while 100% dissimilarity means that no line from the old |
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file made it into the new one. |
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combined diff format |
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-------------------- |
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"git-diff-tree", "git-diff-files" and "git-diff" can take '-c' or |
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'--cc' option to produce 'combined diff'. For showing a merge commit |
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with "git log -p", this is the default format. |
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A 'combined diff' format looks like this: |
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------------ |
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diff --combined describe.c |
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index fabadb8,cc95eb0..4866510 |
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--- a/describe.c |
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+++ b/describe.c |
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@@@ -98,20 -98,12 +98,20 @@@ |
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return (a_date > b_date) ? -1 : (a_date == b_date) ? 0 : 1; |
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} |
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- static void describe(char *arg) |
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-static void describe(struct commit *cmit, int last_one) |
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++static void describe(char *arg, int last_one) |
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{ |
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+ unsigned char sha1[20]; |
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+ struct commit *cmit; |
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struct commit_list *list; |
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static int initialized = 0; |
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struct commit_name *n; |
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+ if (get_sha1(arg, sha1) < 0) |
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+ usage(describe_usage); |
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+ cmit = lookup_commit_reference(sha1); |
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+ if (!cmit) |
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+ usage(describe_usage); |
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+ |
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if (!initialized) { |
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initialized = 1; |
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for_each_ref(get_name); |
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------------ |
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1. It is preceded with a "git diff" header, that looks like |
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this (when '-c' option is used): |
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diff --combined file |
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+ |
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or like this (when '--cc' option is used): |
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diff --c file |
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2. It is followed by one or more extended header lines |
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(this example shows a merge with two parents): |
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index <hash>,<hash>..<hash> |
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mode <mode>,<mode>..<mode> |
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new file mode <mode> |
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deleted file mode <mode>,<mode> |
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+ |
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The `mode <mode>,<mode>..<mode>` line appears only if at least one of |
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the <mode> is different from the rest. Extended headers with |
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information about detected contents movement (renames and |
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copying detection) are designed to work with diff of two |
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<tree-ish> and are not used by combined diff format. |
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3. It is followed by two-line from-file/to-file header |
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--- a/file |
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+++ b/file |
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+ |
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Similar to two-line header for traditional 'unified' diff |
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format, `/dev/null` is used to signal created or deleted |
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files. |
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4. Chunk header format is modified to prevent people from |
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accidentally feeding it to `patch -p1`. Combined diff format |
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was created for review of merge commit changes, and was not |
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meant for apply. The change is similar to the change in the |
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extended 'index' header: |
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@@@ <from-file-range> <from-file-range> <to-file-range> @@@ |
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+ |
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There are (number of parents + 1) `@` characters in the chunk |
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header for combined diff format. |
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Unlike the traditional 'unified' diff format, which shows two |
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files A and B with a single column that has `-` (minus -- |
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appears in A but removed in B), `+` (plus -- missing in A but |
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added to B), or `" "` (space -- unchanged) prefix, this format |
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compares two or more files file1, file2,... with one file X, and |
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shows how X differs from each of fileN. One column for each of |
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fileN is prepended to the output line to note how X's line is |
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different from it. |
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A `-` character in the column N means that the line appears in |
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fileN but it does not appear in the result. A `+` character |
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in the column N means that the line appears in the last file, |
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and fileN does not have that line (in other words, the line was |
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added, from the point of view of that parent). |
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In the above example output, the function signature was changed |
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from both files (hence two `-` removals from both file1 and |
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file2, plus `++` to mean one line that was added does not appear |
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in either file1 nor file2). Also two other lines are the same |
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from file1 but do not appear in file2 (hence prefixed with ` +`). |
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|
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When shown by `git diff-tree -c`, it compares the parents of a |
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merge commit with the merge result (i.e. file1..fileN are the |
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parents). When shown by `git diff-files -c`, it compares the |
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two unresolved merge parents with the working tree file |
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(i.e. file1 is stage 2 aka "our version", file2 is stage 3 aka |
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"their version"). |
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