git diff,git apply和patch小问题三则

Posted on Edited on In

使用补丁维护git仓库时遇到的小问题

1、包含二进制文件时的diff和apply

1
2
3
4
5
6
7
foo$ git diff HEAD^..HEAD > foobar.patch

bar$ git apply foobar.patch
...
error: cannot apply binary patch to 'root/images/back_disabled.png' without full index line
error: root/images/back_disabled.png: patch does not apply
...

git apply提示错误,无法应用补丁。是因为普通的diff格式文件是不支持二进制文件的,新增的或者发生变化的二进制文件无法在diff文件中体现。git扩展了diff使其支持二进制格式,生成补丁时指定选项--binary即可,生成的文件可以顺利的git apply。

1
$ git diff HEAD^..HEAD --binary > foobar.patch

2、git apply的空白问题

1
2
3
4
5
6
$ git apply foobar.patch
foobar.patch:271: trailing whitespace.
foobar.patch:465: space before tab in indent.
 .paging_full_numbers a.paginate_active {
warning: squelched 1705 whitespace errors
warning: 1710 lines add whitespace errors.

看看git apply(1)手册上怎么说:

  • -whitespace=
    When applying a patch, detect a new or modified line that has whitespace errors. What are considered whitespace errors is controlled by core.whitespace configuration. By default, trailing whitespaces (including lines that solely consist of whitespaces) and a space character that is immediately followed by a tab character inside the initial indent of the line are considered whitespace errors.

By default, the command outputs warning messages but applies the patch. When git-apply is used for statistics and not applying a patch, it defaults to nowarn.

You can use different values to control this behavior:

nowarn — turns off the trailing whitespace warning.

warn — outputs warnings for a few such errors, but applies the patch as-is (default).

fix — outputs warnings for a few such errors, and applies the patch after fixing them (strip is a synonym — the tool used to consider only trailing whitespace characters as errors, and the fix involved stripping them, but modern gits do more).

error — outputs warnings for a few such errors, and refuses to apply the patch.

error-all — is similar to error but shows all errors.

git apply应用补丁时会检测空白错误,默认情况下,尾部空白,包含空白的空行,初始tab缩进之后紧跟的空白字符会被认为是错误。
处理这个错误的行为由命令行参数--whitespace或者core.whitespace配置来控制,共有5种可能的动作:

  • nowarn
    关闭错误提示
  • warn
    输出部分错误提示,但完整的应用补丁,不会处理错误,这是默认动作。
  • fix
    输出部分错误,修正错误后应用补丁
  • error
    输出部分错误,拒绝应用补丁。
  • error-all
    输出全部的错误,拒绝应用补丁。

3、patch命令无法处理含有空白的文件名

1
2
3
4
5
6
7
8
9
10
11
12
$ patch p1 < foobar.patch
can't find file to patch at input line 716
Perhaps you used the wrong -p or --strip option?
The text leading up to this was:
--------------------------
diff --git a/root/images/Sorting icons.psd b/root/images/Sorting icons.psd
new file mode 100644
index 0000000..53b2e06
Binary files /dev/null and b/root/images/Sorting icons.psd differ
--------------------------
File to patch: 
Skip this patch? \[y\]

因为diff文件中的文件名含有空格,patch命令无法应用这样的diff补丁。应该避免使用带有特殊字符的文件名。
当然patch也无法引用二进制diff补丁,使用普通diff格式生成含有二进制文件的补丁时,patch会应用成功,但生成的二进制文件是空的。

===
[erq]