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pgdump_reader.go
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pgdump_reader.go
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package pachsql
import (
"bufio"
"io"
"strings"
"github.com/pachyderm/pachyderm/v2/src/internal/errors"
)
// PGDumpReader parses a pgdump file into a header, rows, and a footer
type PGDumpReader struct {
Header []byte
Footer []byte
rd *bufio.Reader
}
// NewPGDumpReader creates a new PGDumpReader
func NewPGDumpReader(r *bufio.Reader) *PGDumpReader {
return &PGDumpReader{
rd: r,
}
}
// ReadRow parses the pgdump file and populates the header and the footer
// It returns EOF when done, and at that time both the Header and Footer will
// be populated. Both header and footer are required. If either are missing, an
// error is returned
func (r *PGDumpReader) ReadRow() ([]byte, error) {
if len(r.Header) == 0 {
err := r.readHeader()
if err != nil {
return nil, err
}
}
endLine := "\\.\n" // Trailing '\.' denotes the end of the row inserts
row, err := r.rd.ReadBytes('\n')
if err != nil && !errors.Is(err, io.EOF) {
return nil, errors.Wrapf(err, "error reading pgdump row")
}
// corner case: some pgdump files separate lines with \r\n (even on linux),
// so clean this case up so all handling below is unified
if len(row) >= 2 && row[len(row)-2] == '\r' {
row[len(row)-2] = '\n'
row = row[:len(row)-1]
}
if string(row) == endLine {
r.Footer = append(r.Footer, row...)
err = r.readFooter()
row = nil // The endline is part of the footer
}
if errors.Is(err, io.EOF) && len(r.Footer) == 0 {
return nil, errors.Errorf("invalid pgdump - missing footer")
}
return row, err
}
func (r *PGDumpReader) readHeader() error {
done := false
for !done {
b, err := r.rd.ReadBytes('\n')
if err != nil {
if errors.Is(err, io.EOF) {
return errors.Errorf("invalid header - missing row inserts")
}
return errors.EnsureStack(err)
}
if strings.HasPrefix(string(b), "COPY") {
done = true
}
r.Header = append(r.Header, b...)
}
return nil
}
func (r *PGDumpReader) readFooter() error {
for {
b, err := r.rd.ReadBytes('\n')
r.Footer = append(r.Footer, b...)
if err != nil {
return errors.EnsureStack(err)
}
}
}