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Limit the max line length when parsing git grep output #30418

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Apr 12, 2024
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20 changes: 16 additions & 4 deletions modules/git/grep.go
Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,7 @@ import (
"errors"
"fmt"
"os"
"slices"
"strconv"
"strings"

Expand All @@ -27,6 +28,7 @@ type GrepOptions struct {
MaxResultLimit int
ContextLineNumber int
IsFuzzy bool
MaxLineLength int // the maximum length of a line to parse, exceeding chars will be truncated
}

func GrepSearch(ctx context.Context, repo *Repository, search string, opts GrepOptions) ([]*GrepResult, error) {
Expand Down Expand Up @@ -71,10 +73,20 @@ func GrepSearch(ctx context.Context, repo *Repository, search string, opts GrepO
defer stdoutReader.Close()

isInBlock := false
scanner := bufio.NewScanner(stdoutReader)
rd := bufio.NewReaderSize(stdoutReader, util.IfZero(opts.MaxLineLength, 16*1024))
var res *GrepResult
for scanner.Scan() {
line := scanner.Text()
for {
lineBytes, isPrefix, err := rd.ReadLine()
if isPrefix {
lineBytes = slices.Clone(lineBytes)
for isPrefix && err == nil {
_, isPrefix, err = rd.ReadLine()
}
}
if len(lineBytes) == 0 && err != nil {
break
}
Comment on lines +86 to +88
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Pity that we now have to treat err != nil as a successful case.
I mean, it does somewhat make sense, but at the same time it probably leads to false negative results.

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Good catch. Actually I have thought about this change and I think it should be good enough.

The real cases for returning "err" in this "grep" functions:

  1. Command fails, the error is returned by "cmd.Run"
  2. Pipe fails (this case), I think it would seldom happen in real life. Even if happens, returning partially parsed results is still better than showing a 500 error page.

line := string(lineBytes) // the memory of lineBytes is mutable
if !isInBlock {
if _ /* ref */, filename, ok := strings.Cut(line, ":"); ok {
isInBlock = true
Expand All @@ -100,7 +112,7 @@ func GrepSearch(ctx context.Context, repo *Repository, search string, opts GrepO
res.LineCodes = append(res.LineCodes, lineCode)
}
}
return scanner.Err()
return nil
},
})
// git grep exits by cancel (killed), usually it is caused by the limit of results
Expand Down
10 changes: 10 additions & 0 deletions modules/git/grep_test.go
Original file line number Diff line number Diff line change
Expand Up @@ -41,6 +41,16 @@ func TestGrepSearch(t *testing.T) {
},
}, res)

res, err = GrepSearch(context.Background(), repo, "void", GrepOptions{MaxResultLimit: 1, MaxLineLength: 39})
assert.NoError(t, err)
assert.Equal(t, []*GrepResult{
{
Filename: "java-hello/main.java",
LineNumbers: []int{3},
LineCodes: []string{" public static void main(String[] arg"},
},
}, res)

res, err = GrepSearch(context.Background(), repo, "no-such-content", GrepOptions{})
assert.NoError(t, err)
assert.Len(t, res, 0)
Expand Down