Steffen ProhaskaHere is the current version of the safecrlf patch. It applies to the post 1.5.4 master and has the following changes since v5: - Uses git config instead of git repo-config. - The tests use test_expect_success.
Steffen
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CRLF conversion bears a slight chance of corrupting data. autocrlf=true will convert CRLF to LF during commit and LF to CRLF during checkout. A file that contains a mixture of LF and CRLF before the commit cannot be recreated by git. For text files this does not really matter because we do not care about the line endings anyway; but for binary files that are accidentally classified as text the conversion can corrupt data.
If you recognize such corruption early you can easily fix it by setting the conversion type explicitly in .gitattributes. Right after committing you still have the original file in your work tree and this file is not yet corrupted. You can explicitly tell git that this file is binary and git will handle the file appropriately.
In mixed Windows/Unix environments text files quite easily can end up containing a mixture of CRLF and LF line endings and git should handle such situations gracefully. For example, a user could copy a CRLF file from Windows to Unix and mix it with an existing LF file there. The result would contain both types of line endings.
Unfortunately, the desired effect of cleaning up text files with mixed line endings and the undesired effect of corrupting binary files can not be distinguished. In both cases CRLF endings are removed in an irreversible way. For text files this is the right thing to do, while for binary file it corrupts data.
In a sane environment, committing and checking out the same file should not modify the original file in the work tree. For autocrlf=input the original file must not contain CRLF. For autocrlf=true the original file must not contain LF without preceding CR. Otherwise the conversion is irreversible. Note, git might be able to recreate the original file with different autocrlf settings, but in the current environment checking out will yield a file that differs from the file before the commit.
This patch adds a mechanism that can either warn the user about an irreversible conversion or can even refuse to convert. The mechanism is controlled by the variable core.safecrlf, with the following values - false: disable safecrlf mechanism - warn: warn about irreversible conversions - true: refuse irreversible conversions
The default is to warn.
The safecrlf mechanism's details depend on the git command. If safecrlf is active (not false), files in the work tree must not be modified in an irreversible way without giving the user a chance to backup the original file. However, for read-only operations that do not modify files in the work tree git should not print annoying warnings.
This commit modifies git apply to fail even if safecrlf=warn, because git apply writes its changes back to the work tree immediately. The user would not have a chance to backup the old version of the file if only a warning was printed. Hence, a warning isn't sufficient and we should fail instead.
git diff, git add, and any other command that calls index_fd(..., write_object=1) behave exactly as requested by safecrlf. The user still has the chance to save her data before checkout or applying the diff.
git blame will never warn nor fail because it never writes to the work tree.
The concept of a safety check was originally proposed in a similar way by Linus Torvalds. Thanks to Dimitry Potapov for insisting on getting the naked LF/autocrlf=true case right.
Signed-off-by: Steffen Prohaska <prohaska@zib.de> --- Documentation/config.txt | 22 +++++++++++++++ Documentation/gitattributes.txt | 5 +++ builtin-apply.c | 2 +- builtin-blame.c | 2 +- cache.h | 10 ++++++- config.c | 9 ++++++ convert.c | 34 +++++++++++++++++++---- diff.c | 2 +- environment.c | 1 + sha1_file.c | 2 +- t/t0020-crlf.sh | 58 +++++++++++++++++++++++++++++++++++++++ 11 files changed, 136 insertions(+), 11 deletions(-)
Show changes to 11 files +136 −11
Documentation/config.txt, Documentation/gitattributes.txt, builtin-apply.c, builtin-blame.c, cache.h, config.c, convert.c, diff.c, environment.c, sha1_file.c, t/t0020-crlf.sh
diff --git a/Documentation/config.txt b/Documentation/config.txt index 4e222f1..b1b5c67 100644 --- a/Documentation/config.txt +++ b/Documentation/config.txt @@ -139,6 +139,28 @@ core.autocrlf:: "text" (i.e. be subjected to the autocrlf mechanism) is decided purely based on the contents. +core.safecrlf:: + If true, makes git check if converting `CRLF` as controlled by + `core.autocrlf` is reversible. Git will check if a command + modifies a file in the work tree either directly or indirectly. + For example, committing a file followed by checking out the + same file should yield the original file in the work tree. If + this is not the case for the current setting of + `core.autocrlf`, git will reject the file. The variable can + be set to "warn", in which case git will only warn about an + irreversible conversion but accept the file. ++ +Note, this safety check does not mean that a checkout will generate a +file identical to the original file for different settings of +`core.autocrlf`, but only for the current one. For example, a text +file with `LF` would be accepted with `core.autocrlf=input` and could +later be checked out with `core.autocrlf=true`, in which case the +resulting file would contain `CRLF`, although the original file +contained `LF`. However, in both work trees the line endings would be +consistent, that is either all `LF` or all `CRLF`, but never mixed. A +file with mixed line endings would be reported by the `core.safecrlf` +mechanism. + core.symlinks:: If false, symbolic links are checked out as small plain files that contain the link text. linkgit:git-update-index[1] and diff --git a/Documentation/gitattributes.txt b/Documentation/gitattributes.txt index 35a29fd..2ffe1fb 100644 --- a/Documentation/gitattributes.txt +++ b/Documentation/gitattributes.txt @@ -133,6 +133,11 @@ When `core.autocrlf` is set to "input", line endings are converted to LF upon checkin, but there is no conversion done upon checkout. +If `core.safecrlf` is set to "true" or "warn", git verifies if +the conversion is reversible for the current setting of +`core.autocrlf`. For "true", git rejects irreversible +conversions; for "warn", git only prints a warning but accepts +an irreversible conversion. `ident` ^^^^^^^ diff --git a/builtin-apply.c b/builtin-apply.c index 15432b6..e487936 100644 --- a/builtin-apply.c +++ b/builtin-apply.c @@ -1430,7 +1430,7 @@ static int read_old_data(struct stat *st, const char *path, struct strbuf *buf) case S_IFREG: if (strbuf_read_file(buf, path, st->st_size) != st->st_size) return error("unable to open or read %s", path); - convert_to_git(path, buf->buf, buf->len, buf); + convert_to_git(path, buf->buf, buf->len, buf, safe_crlf ? SAFE_CRLF_FAIL : 0); return 0; default: return -1; diff --git a/builtin-blame.c b/builtin-blame.c index 9b4c02e..c361ee1 100644 --- a/builtin-blame.c +++ b/builtin-blame.c @@ -2073,7 +2073,7 @@ static struct commit *fake_working_tree_commit(const char *path, const char *con if (strbuf_read(&buf, 0, 0) < 0) die("read error %s from stdin", strerror(errno)); } - convert_to_git(path, buf.buf, buf.len, &buf); + convert_to_git(path, buf.buf, buf.len, &buf, 0); origin->file.ptr = buf.buf; origin->file.size = buf.len; pretend_sha1_file(buf.buf, buf.len, OBJ_BLOB, origin->blob_sha1); diff --git a/cache.h b/cache.h index 549f4bb..f8223a6 100644 --- a/cache.h +++ b/cache.h @@ -330,6 +330,14 @@ extern size_t packed_git_limit; extern size_t delta_base_cache_limit; extern int auto_crlf; +enum safe_crlf { + SAFE_CRLF_FALSE = 0, + SAFE_CRLF_FAIL = 1, + SAFE_CRLF_WARN = 2, +}; + +extern enum safe_crlf safe_crlf; + #define GIT_REPO_VERSION 0 extern int repository_format_version; extern int check_repository_format(void); @@ -633,7 +641,7 @@ extern void trace_argv_printf(const char **argv, const char *format, ...); /* convert.c */ /* returns 1 if *dst was used */ -extern int convert_to_git(const char *path, const char *src, size_t len, struct strbuf *dst); +extern int convert_to_git(const char *path, const char *src, size_t len, struct strbuf *dst, enum safe_crlf checksafe); extern int convert_to_working_tree(const char *path, const char *src, size_t len, struct strbuf *dst); /* add */ diff --git a/config.c b/config.c index 526a3f4..5fe7cce 100644 --- a/config.c +++ b/config.c @@ -407,6 +407,15 @@ int git_default_config(const char *var, const char *value) return 0; } + if (!strcmp(var, "core.safecrlf")) { + if (value && !strcasecmp(value, "warn")) { + safe_crlf = SAFE_CRLF_WARN; + return 0; + } + safe_crlf = git_config_bool(var, value); + return 0; + } + if (!strcmp(var, "user.name")) { strlcpy(git_default_name, value, sizeof(git_default_name)); return 0; diff --git a/convert.c b/convert.c index 80f114b..d580a62 100644 --- a/convert.c +++ b/convert.c @@ -86,7 +86,7 @@ static int is_binary(unsigned long size, struct text_stat *stats) } static int crlf_to_git(const char *path, const char *src, size_t len, - struct strbuf *buf, int action) + struct strbuf *buf, int action, enum safe_crlf checksafe) { struct text_stat stats; char *dst; @@ -95,9 +95,6 @@ static int crlf_to_git(const char *path, const char *src, size_t len, return 0; gather_stats(src, len, &stats); - /* No CR? Nothing to convert, regardless. */ - if (!stats.cr) - return 0; if (action == CRLF_GUESS) { /* @@ -115,6 +112,30 @@ static int crlf_to_git(const char *path, const char *src, size_t len, return 0; } + if (checksafe) { + if (action == CRLF_INPUT || auto_crlf <= 0) { + /* CRLFs would not be restored by checkout: check if we'd remove CRLFs */ + if (stats.crlf) { + if (checksafe == SAFE_CRLF_WARN) + warning("CRLF will be replaced by LF in %s.", path); + else + die("CRLF would be replaced by LF in %s.", path); + } + } else if (auto_crlf > 0) { + /* CRLFs would be added by checkout: check if we have "naked" LFs */ + if (stats.lf != stats.crlf) { + if (checksafe == SAFE_CRLF_WARN) + warning("LFs will be replaced by CRLF in %s", path); + else + die("LF would be replaced by CRLF in %s", path); + } + } + } + + /* Optimization: No CR? Nothing to convert, regardless. */ + if (!stats.cr) + return 0; + /* only grow if not in place */ if (strbuf_avail(buf) + buf->len < len) strbuf_grow(buf, len - buf->len); @@ -536,7 +557,8 @@ static int git_path_check_ident(const char *path, struct git_attr_check *check) return !!ATTR_TRUE(value); } -int convert_to_git(const char *path, const char *src, size_t len, struct strbuf *dst) +int convert_to_git(const char *path, const char *src, size_t len, + struct strbuf *dst, enum safe_crlf checksafe) { struct git_attr_check check[3]; int crlf = CRLF_GUESS; @@ -558,7 +580,7 @@ int convert_to_git(const char *path, const char *src, size_t len, struct strbuf src = dst->buf; len = dst->len; } - ret |= crlf_to_git(path, src, len, dst, crlf); + ret |= crlf_to_git(path, src, len, dst, crlf, checksafe); if (ret) { src = dst->buf; len = dst->len; diff --git a/diff.c b/diff.c index 5b8afdc..562c20e 100644 --- a/diff.c +++ b/diff.c @@ -1624,7 +1624,7 @@ int diff_populate_filespec(struct diff_filespec *s, int size_only) * Convert from working tree format to canonical git format */ strbuf_init(&buf, 0); - if (convert_to_git(s->path, s->data, s->size, &buf)) { + if (convert_to_git(s->path, s->data, s->size, &buf, safe_crlf)) { size_t size = 0; munmap(s->data, s->size); s->should_munmap = 0; diff --git a/environment.c b/environment.c index 18a1c4e..e351e99 100644 --- a/environment.c +++ b/environment.c @@ -35,6 +35,7 @@ int pager_use_color = 1; char *editor_program; char *excludes_file; int auto_crlf = 0; /* 1: both ways, -1: only when adding git objects */ +enum safe_crlf safe_crlf = SAFE_CRLF_WARN; unsigned whitespace_rule_cfg = WS_DEFAULT_RULE; /* This is set by setup_git_dir_gently() and/or git_default_config() */ diff --git a/sha1_file.c b/sha1_file.c index 66a4e00..1cf8337 100644 --- a/sha1_file.c +++ b/sha1_file.c @@ -2358,7 +2358,7 @@ int index_fd(unsigned char *sha1, int fd, struct stat *st, int write_object, if ((type == OBJ_BLOB) && S_ISREG(st->st_mode)) { struct strbuf nbuf; strbuf_init(&nbuf, 0); - if (convert_to_git(path, buf, size, &nbuf)) { + if (convert_to_git(path, buf, size, &nbuf, write_object ? safe_crlf : 0)) { munmap(buf, size); buf = strbuf_detach(&nbuf, &size); re_allocated = 1; diff --git a/t/t0020-crlf.sh b/t/t0020-crlf.sh index 8b27aa8..90ea081 100755 --- a/t/t0020-crlf.sh +++ b/t/t0020-crlf.sh @@ -8,6 +8,10 @@ q_to_nul () { tr Q '\000' } +q_to_cr () { + tr Q '\015' +} + append_cr () { sed -e 's/$/Q/' | tr Q '\015' } @@ -42,6 +46,60 @@ test_expect_success setup ' echo happy. ' +test_expect_success 'safecrlf: autocrlf=input, all CRLF' ' + + git config core.autocrlf input && + git config core.safecrlf true && + + for w in I am all CRLF; do echo $w; done | append_cr >allcrlf && + ! git add allcrlf +' + +test_expect_success 'safecrlf: autocrlf=input, mixed LF/CRLF' ' + + git config core.autocrlf input && + git config core.safecrlf true && + + for w in Oh here is CRLFQ in text; do echo $w; done | q_to_cr >mixed && + ! git add mixed +' + +test_expect_success 'safecrlf: autocrlf=true, all LF' ' + + git config core.autocrlf true && + git config core.safecrlf true && + + for w in I am all LF; do echo $w; done >alllf && + ! git add alllf +' + +test_expect_success 'safecrlf: autocrlf=true mixed LF/CRLF' ' + + git config core.autocrlf true && + git config core.safecrlf true && + + for w in Oh here is CRLFQ in text; do echo $w; done | q_to_cr >mixed && + ! git add mixed +' + +test_expect_success 'safecrlf: print warning only once' ' + + git config core.autocrlf input && + git config core.safecrlf warn && + + for w in I am all LF; do echo $w; done >doublewarn && + git add doublewarn && + git commit -m "nowarn" && + for w in Oh here is CRLFQ in text; do echo $w; done | q_to_cr >doublewarn && + test $(git add doublewarn 2>&1 | grep "CRLF will be replaced by LF" | wc -l) = 1 +' + +test_expect_success 'switch off autocrlf, safecrlf, reset HEAD' ' + git config core.autocrlf false && + git config core.safecrlf false && + git reset --hard HEAD^ +' + test_expect_success 'update with autocrlf=input' ' rm -f tmp one dir/two three &&
-- 1.5.4.rc5.33.gc24ec
