| // Copyright 2009 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| // Package patch implements parsing and execution of the textual and |
| // binary patch descriptions used by version control tools such as |
| // CVS, Git, Mercurial, and Subversion. |
| package patch |
| |
| import ( |
| "bytes" |
| "os" |
| "path" |
| "strings" |
| ) |
| |
| // A Set represents a set of patches to be applied as a single atomic unit. |
| // Patch sets are often preceded by a descriptive header. |
| type Set struct { |
| Header string // free-form text |
| File []*File |
| } |
| |
| // A File represents a collection of changes to be made to a single file. |
| type File struct { |
| Verb Verb |
| Src string // source for Verb == Copy, Verb == Rename |
| Dst string |
| OldMode, NewMode int // 0 indicates not used |
| Diff // changes to data; == NoDiff if operation does not edit file |
| } |
| |
| // A Verb is an action performed on a file. |
| type Verb string |
| |
| const ( |
| Add Verb = "add" |
| Copy Verb = "copy" |
| Delete Verb = "delete" |
| Edit Verb = "edit" |
| Rename Verb = "rename" |
| ) |
| |
| // A Diff is any object that describes changes to transform |
| // an old byte stream to a new one. |
| type Diff interface { |
| // Apply applies the changes listed in the diff |
| // to the string s, returning the new version of the string. |
| // Note that the string s need not be a text string. |
| Apply(old []byte) (new []byte, err os.Error) |
| } |
| |
| // NoDiff is a no-op Diff implementation: it passes the |
| // old data through unchanged. |
| var NoDiff Diff = noDiffType(0) |
| |
| type noDiffType int |
| |
| func (noDiffType) Apply(old []byte) ([]byte, os.Error) { |
| return old, nil |
| } |
| |
| // A SyntaxError represents a syntax error encountered while parsing a patch. |
| type SyntaxError string |
| |
| func (e SyntaxError) String() string { return string(e) } |
| |
| var newline = []byte{'\n'} |
| |
| // Parse patches the patch text to create a patch Set. |
| // The patch text typically comprises a textual header and a sequence |
| // of file patches, as would be generated by CVS, Subversion, |
| // Mercurial, or Git. |
| func Parse(text []byte) (*Set, os.Error) { |
| // Split text into files. |
| // CVS and Subversion begin new files with |
| // Index: file name. |
| // ================== |
| // diff -u blah blah |
| // |
| // Mercurial and Git use |
| // diff [--git] a/file/path b/file/path. |
| // |
| // First look for Index: lines. If none, fall back on diff lines. |
| text, files := sections(text, "Index: ") |
| if len(files) == 0 { |
| text, files = sections(text, "diff ") |
| } |
| |
| set := &Set{string(text), make([]*File, len(files))} |
| |
| // Parse file header and then |
| // parse files into patch chunks. |
| // Each chunk begins with @@. |
| for i, raw := range files { |
| p := new(File) |
| set.File[i] = p |
| |
| // First line of hdr is the Index: that |
| // begins the section. After that is the file name. |
| s, raw, _ := getLine(raw, 1) |
| if hasPrefix(s, "Index: ") { |
| p.Dst = string(bytes.TrimSpace(s[7:])) |
| goto HaveName |
| } else if hasPrefix(s, "diff ") { |
| str := string(bytes.TrimSpace(s)) |
| i := strings.LastIndex(str, " b/") |
| if i >= 0 { |
| p.Dst = str[i+3:] |
| goto HaveName |
| } |
| } |
| return nil, SyntaxError("unexpected patch header line: " + string(s)) |
| HaveName: |
| p.Dst = path.Clean(p.Dst) |
| if strings.HasPrefix(p.Dst, "../") || strings.HasPrefix(p.Dst, "/") { |
| return nil, SyntaxError("invalid path: " + p.Dst) |
| } |
| |
| // Parse header lines giving file information: |
| // new file mode %o - file created |
| // deleted file mode %o - file deleted |
| // old file mode %o - file mode changed |
| // new file mode %o - file mode changed |
| // rename from %s - file renamed from other file |
| // rename to %s |
| // copy from %s - file copied from other file |
| // copy to %s |
| p.Verb = Edit |
| for len(raw) > 0 { |
| oldraw := raw |
| var l []byte |
| l, raw, _ = getLine(raw, 1) |
| l = bytes.TrimSpace(l) |
| if m, s, ok := atoi(l, "new file mode ", 8); ok && len(s) == 0 { |
| p.NewMode = m |
| p.Verb = Add |
| continue |
| } |
| if m, s, ok := atoi(l, "deleted file mode ", 8); ok && len(s) == 0 { |
| p.OldMode = m |
| p.Verb = Delete |
| p.Src = p.Dst |
| p.Dst = "" |
| continue |
| } |
| if m, s, ok := atoi(l, "old file mode ", 8); ok && len(s) == 0 { |
| // usually implies p.Verb = "rename" or "copy" |
| // but we'll get that from the rename or copy line. |
| p.OldMode = m |
| continue |
| } |
| if m, s, ok := atoi(l, "old mode ", 8); ok && len(s) == 0 { |
| p.OldMode = m |
| continue |
| } |
| if m, s, ok := atoi(l, "new mode ", 8); ok && len(s) == 0 { |
| p.NewMode = m |
| continue |
| } |
| if s, ok := skip(l, "rename from "); ok && len(s) > 0 { |
| p.Src = string(s) |
| p.Verb = Rename |
| continue |
| } |
| if s, ok := skip(l, "rename to "); ok && len(s) > 0 { |
| p.Verb = Rename |
| continue |
| } |
| if s, ok := skip(l, "copy from "); ok && len(s) > 0 { |
| p.Src = string(s) |
| p.Verb = Copy |
| continue |
| } |
| if s, ok := skip(l, "copy to "); ok && len(s) > 0 { |
| p.Verb = Copy |
| continue |
| } |
| if s, ok := skip(l, "Binary file "); ok && len(s) > 0 { |
| // Hg prints |
| // Binary file foo has changed |
| // when deleting a binary file. |
| continue |
| } |
| if s, ok := skip(l, "RCS file: "); ok && len(s) > 0 { |
| // CVS prints |
| // RCS file: /cvs/plan9/bin/yesterday,v |
| // retrieving revision 1.1 |
| // for each file. |
| continue |
| } |
| if s, ok := skip(l, "retrieving revision "); ok && len(s) > 0 { |
| // CVS prints |
| // RCS file: /cvs/plan9/bin/yesterday,v |
| // retrieving revision 1.1 |
| // for each file. |
| continue |
| } |
| if hasPrefix(l, "===") || hasPrefix(l, "---") || hasPrefix(l, "+++") || hasPrefix(l, "diff ") { |
| continue |
| } |
| if hasPrefix(l, "@@ -") { |
| diff, err := ParseTextDiff(oldraw) |
| if err != nil { |
| return nil, err |
| } |
| p.Diff = diff |
| break |
| } |
| if hasPrefix(l, "GIT binary patch") || (hasPrefix(l, "index ") && !hasPrefix(raw, "--- ")) { |
| diff, err := ParseGitBinary(oldraw) |
| if err != nil { |
| return nil, err |
| } |
| p.Diff = diff |
| break |
| } |
| if hasPrefix(l, "index ") { |
| continue |
| } |
| return nil, SyntaxError("unexpected patch header line: " + string(l)) |
| } |
| if p.Diff == nil { |
| p.Diff = NoDiff |
| } |
| if p.Verb == Edit { |
| p.Src = p.Dst |
| } |
| } |
| |
| return set, nil |
| } |
| |
| // getLine returns the first n lines of data and the remainder. |
| // If data has no newline, getLine returns data, nil, false |
| func getLine(data []byte, n int) (first []byte, rest []byte, ok bool) { |
| rest = data |
| ok = true |
| for ; n > 0; n-- { |
| nl := bytes.Index(rest, newline) |
| if nl < 0 { |
| rest = nil |
| ok = false |
| break |
| } |
| rest = rest[nl+1:] |
| } |
| first = data[0 : len(data)-len(rest)] |
| return |
| } |
| |
| // sections returns a collection of file sections, |
| // each of which begins with a line satisfying prefix. |
| // text before the first instance of such a line is |
| // returned separately. |
| func sections(text []byte, prefix string) ([]byte, [][]byte) { |
| n := 0 |
| for b := text; ; { |
| if hasPrefix(b, prefix) { |
| n++ |
| } |
| nl := bytes.Index(b, newline) |
| if nl < 0 { |
| break |
| } |
| b = b[nl+1:] |
| } |
| |
| sect := make([][]byte, n+1) |
| n = 0 |
| for b := text; ; { |
| if hasPrefix(b, prefix) { |
| sect[n] = text[0 : len(text)-len(b)] |
| n++ |
| text = b |
| } |
| nl := bytes.Index(b, newline) |
| if nl < 0 { |
| sect[n] = text |
| break |
| } |
| b = b[nl+1:] |
| } |
| return sect[0], sect[1:] |
| } |
| |
| // if s begins with the prefix t, skip returns |
| // s with that prefix removed and ok == true. |
| func skip(s []byte, t string) (ss []byte, ok bool) { |
| if len(s) < len(t) || string(s[0:len(t)]) != t { |
| return nil, false |
| } |
| return s[len(t):], true |
| } |
| |
| // if s begins with the prefix t and then is a sequence |
| // of digits in the given base, atoi returns the number |
| // represented by the digits and s with the |
| // prefix and the digits removed. |
| func atoi(s []byte, t string, base int) (n int, ss []byte, ok bool) { |
| if s, ok = skip(s, t); !ok { |
| return |
| } |
| var i int |
| for i = 0; i < len(s) && '0' <= s[i] && s[i] <= byte('0'+base-1); i++ { |
| n = n*base + int(s[i]-'0') |
| } |
| if i == 0 { |
| return |
| } |
| return n, s[i:], true |
| } |
| |
| // hasPrefix returns true if s begins with t. |
| func hasPrefix(s []byte, t string) bool { |
| _, ok := skip(s, t) |
| return ok |
| } |
| |
| // splitLines returns the result of splitting s into lines. |
| // The \n on each line is preserved. |
| func splitLines(s []byte) [][]byte { return bytes.SplitAfter(s, newline, -1) } |