如何确定 Git 是以二进制文件还是以文本形式处理文件？

我知道 Git 以某种方式自动检测文件是二进制文件还是文本文件，如果需要，可以使用 .gitattributes手动设置。但是，是否还有一种方法可以询问 Git 如何处理文件呢？

假设我有一个包含两个文件的 Git 存储库: 一个包含纯文本的 ascii.dat文件和一个包含随机二进制文件的 binary.dat文件。Git 将第一个 .dat文件作为文本处理，将第二个文件作为二进制文件处理。现在我想编写一个 Git web 前端，它有一个文本文件查看器和一个二进制文件特殊查看器(例如显示十六进制转储)。当然，我可以实现我自己的文本/二进制检查，但是如果查看器依赖于 Git 如何处理这些文件的信息，那么它会更有用。

那么，我怎样才能问 Git 它是将文件作为文本还是二进制文件对待呢？

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小开

I don't like this answer, but you can parse the output of git-diff-tree to see if it is binary. For example:

git diff-tree -p 4b825dc642cb6eb9a060e54bf8d69288fbee4904 HEAD -- MegaCli
diff --git a/megaraid/MegaCli b/megaraid/MegaCli
new file mode 100755
index 0000000..7f0e997
Binary files /dev/null and b/megaraid/MegaCli differ

as opposed to:

git diff-tree -p 4b825dc642cb6eb9a060e54bf8d69288fbee4904 HEAD -- megamgr
diff --git a/megaraid/megamgr b/megaraid/megamgr
new file mode 100755
index 0000000..50fd8a1
--- /dev/null
+++ b/megaraid/megamgr
@@ -0,0 +1,78 @@
+#!/bin/sh
[…]

Oh, and BTW, 4b825d… is a magic SHA which represents the empty tree (it is the SHA for an empty tree, but git is specially aware of this magic).

小开
最佳答案

builtin_diff()1 calls diff_filespec_is_binary() which calls buffer_is_binary() which checks for any occurrence of a zero byte (NUL “character”) in the first 8000 bytes (or the entire length if shorter).

I do not see that this “is it binary?” test is explicitly exposed in any command though.

git merge-file directly uses buffer_is_binary(), so you may be able to make use of it:

git merge-file /dev/null /dev/null file-to-test

It seems to produce the error message like error: Cannot merge binary files: file-to-test and yields an exit status of 255 when given a binary file. I am not sure I would want to rely on this behavior though.

Maybe git diff --numstat would be more reliable:

isBinary() {
p=$(printf '%s\t-\t' -)
t=$(git diff --no-index --numstat /dev/null "$1")
case "$t" in "$p"*) return 0 ;; esac
return 1
}
isBinary file-to-test && echo binary || echo not binary

For binary files, the --numstat output should start with - TAB - TAB, so we just test for that.

1 builtin_diff() has strings like Binary files %s and %s differ that should be familiar.

小开 
git grep -I --name-only --untracked -e . -- ascii.dat binary.dat ...

will return the names of files that git interprets as text files.

The trick here is in these two git grep parameters:

  • -I: Don’t match the pattern in binary files.
  • -e .: Regular expression match any character in the file

You can use wildcards e.g.

git grep -I --name-only --untracked -e . -- *.ps1
小开

You can use command-line tool 'file' utility. On Windows it's included in git installation and normally located in in C:\Program Files\git\usr\bin folder

file --mime-encoding *

See more in Get encoding of a file in Windows

小开

At the risk of getting slapped for poor code quality, I'm listing a C utility, is_binary, built around the original buffer_is_binary() routine in the Git source. Please see internal comments for how to build and run. Easily modifyable:

/***********************************************************
* is_binary.c
*
* Usage: is_binary <pathname>
*   Returns a 1 if a binary; return a 0 if non-binary
*
* Thanks to Git and Stackoverflow developers for helping with these routines:
* - the buffer_is_binary() routine from the xdiff-interface.c module
*   in git source code.
* - the read-a-filename-from-stdin route
* - the read-a-file-into-memory (fill_buffer()) routine
*
* To build:
*    % gcc is_binary.c -o is_binary
*
* To build debuggable (to push a few messages to stdout):
*    % gcc -DDEBUG=1 ./is_binary.c -o is_binary
*
* BUGS:
*  Doesn't work with piped input, like
*    % cat foo.tar | is_binary
*  Claims that zero input is binary. Actually,
*  what should it be?
*
* Revision 1.4
*
* Tue Sep 12 09:01:33 EDT 2017
***********************************************************/
#include <string.h>
#include <stdio.h>
#include <stdlib.h>


#define MAX_PATH_LENGTH 200
#define FIRST_FEW_BYTES 8000


/* global, unfortunately */
char *source_blob_buffer;


/* From: https://stackoverflow.com/questions/14002954/c-programming-how-to-read-the-whole-file-contents-into-a-buffer */


/* From: https://stackoverflow.com/questions/1563882/reading-a-file-name-from-piped-command */


/* From: https://stackoverflow.com/questions/6119956/how-to-determine-if-git-handles-a-file-as-binary-or-as-text
*/


/* The key routine in this function is from libc: void *memchr(const void *s, int c, size_t n); */
/* Checks for any occurrence of a zero byte (NUL character) in the first 8000 bytes (or the entire length if shorter). */


int buffer_is_binary(const char *ptr, unsigned long size)
{
if (FIRST_FEW_BYTES < size)
size = FIRST_FEW_BYTES;
/* printf("buff = %s.\n", ptr); */
return !!memchr(ptr, 0, size);
}
int fill_buffer(FILE * file_object_pointer) {
fseek(file_object_pointer, 0, SEEK_END);
long fsize = ftell(file_object_pointer);
fseek(file_object_pointer, 0, SEEK_SET);  //same as rewind(f);
source_blob_buffer = malloc(fsize + 1);
fread(source_blob_buffer, fsize, 1, file_object_pointer);
fclose(file_object_pointer);
source_blob_buffer[fsize] = 0;
return (fsize + 1);
}
int main(int argc, char *argv[]) {


char pathname[MAX_PATH_LENGTH];
FILE *file_object_pointer;


if (argc == 1) {
file_object_pointer = stdin;
} else {
strcpy(pathname,argv[1]);
#ifdef DEBUG
printf("pathname=%s.\n", pathname);
#endif
file_object_pointer = fopen (pathname, "rb");
if (file_object_pointer == NULL) {
printf ("I'm sorry, Dave, I can't do that--");
printf ("open the file '%s', that is.\n", pathname);
exit(3);
}
}
if (!file_object_pointer) {
printf("Not a file nor a pipe--sorry.\n");
exit (4);
}
int fsize = fill_buffer(file_object_pointer);
int result = buffer_is_binary(source_blob_buffer, fsize - 2);


#ifdef DEBUG
if (result == 1) {
printf ("%s %d\n", pathname, fsize - 1);
}
else {
printf ("File '%s' is NON-BINARY; size is %d bytes.\n", pathname, fsize - 1);
}
#endif
exit(result);
/* easy check -- 'echo $?' after running */
}
小开

@bonh gave a working answer in a comment

git diff --numstat 4b825dc642cb6eb9a060e54bf8d69288fbee4904 HEAD -- | grep "^-" | cut -f 3

It shows all files which git interprets as binaries.

小开 
# considered binary (or with bare CR) file
git ls-files --eol | grep -E '^(i/-text)'


# files that do not have any line-ending characters (including empty files) - unlikely that this is a true binary file ?
git ls-files --eol | grep -E '^(i/none)'


#                                                        via experimentation
#                                                      ------------------------
#    "-text"        binary (or with bare CR) file     : not    auto-normalized
#    "none"         text file without any EOL         : not    auto-normalized
#    "lf"           text file with LF                 : is     auto-normalized when gitattributes text=auto
#    "crlf"         text file with CRLF               : is     auto-normalized when gitattributes text=auto
#    "mixed"        text file with mixed line endings : is     auto-normalized when gitattributes text=auto
#                   (LF or CRLF, but not bare CR)

Source: https://git-scm.com/docs/git-ls-files#Documentation/git-ls-files.txt---eol https://github.com/git/git/commit/a7630bd4274a0dff7cff8b92de3d3f064e321359

Oh by the way: be careful with setting the .gitattributes text attribute e.g. *.abc text. Because in that case all files with *.abc will be normalized, even if they are binary (internal CRLF found in the binary would be normalized to LF). This is different from the auto behaviour.

小开

Use git check-attr --all.

This works regardless of if the file has been staged/committed or not.

Tested on git version 2.30.2.

Assuming you have this in .gitattributes.

package-lock.json binary

There is this output.

git check-attr --all package-lock.json
package-lock.json: binary: set
package-lock.json: diff: unset
package-lock.json: merge: unset
package-lock.json: text: unset

For normal files, there is no output.

git check-attr --all package.json

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