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git/vcs-svn/line_buffer.h

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Add stream helper library This library provides thread-unsafe fgets()- and fread()-like functions where the caller does not have to supply a buffer. It maintains a couple of static buffers and provides an API to use them. [rr: allow input from files other than stdin] [jn: with tests, documentation, and error handling improvements] Signed-off-by: David Barr <david.barr@cordelta.com> Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com> Signed-off-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
14 years ago
#ifndef LINE_BUFFER_H_
#define LINE_BUFFER_H_
vcs-svn: collect line_buffer data in a struct Prepare for the line_buffer lib to support input from multiple files, by collecting global state in a struct that can be easily passed around. No API change yet. Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
14 years ago
#include "strbuf.h"
#define LINE_BUFFER_LEN 10000
struct line_buffer {
char line_buffer[LINE_BUFFER_LEN];
struct strbuf blob_buffer;
FILE *infile;
};
#define LINE_BUFFER_INIT {"", STRBUF_INIT, NULL}
vcs-svn: teach line_buffer to handle multiple input files Collect the line_buffer state in a newly public line_buffer struct. Callers can use multiple line_buffers to manage input from multiple files at a time. svn-fe's delta applier will use this to stream a delta from svnrdump and the preimage it applies to from fast-import at the same time. The tests don't take advantage of the new features, but I think that's okay. It is easier to find lingering examples of nonreentrant code by searching for "static" in line_buffer.c. Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
14 years ago
int buffer_init(struct line_buffer *buf, const char *filename);
vcs-svn: allow input from file descriptor Based-on-patch-by: David Barr <david.barr@cordelta.com> Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
14 years ago
int buffer_fdinit(struct line_buffer *buf, int fd);
vcs-svn: teach line_buffer to handle multiple input files Collect the line_buffer state in a newly public line_buffer struct. Callers can use multiple line_buffers to manage input from multiple files at a time. svn-fe's delta applier will use this to stream a delta from svnrdump and the preimage it applies to from fast-import at the same time. The tests don't take advantage of the new features, but I think that's okay. It is easier to find lingering examples of nonreentrant code by searching for "static" in line_buffer.c. Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
14 years ago
int buffer_deinit(struct line_buffer *buf);
vcs-svn: teach line_buffer about temporary files It can sometimes be useful to write information temporarily to file, to read back later. These functions allow a program to use the line_buffer facilities when doing so. It works like this: 1. find a unique filename with buffer_tmpfile_init. 2. rewind with buffer_tmpfile_rewind. This returns a stdio handle for writing. 3. when finished writing, declare so with buffer_tmpfile_prepare_to_read. The return value indicates how many bytes were written. 4. read whatever portion of the file is needed. 5. if finished, remove the temporary file with buffer_deinit. otherwise, go back to step 2, The svn support would use this to buffer the postimage from delta application until the length is known and fast-import can receive the resulting blob. Based-on-patch-by: David Barr <david.barr@cordelta.com> Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
14 years ago
void buffer_reset(struct line_buffer *buf);
int buffer_tmpfile_init(struct line_buffer *buf);
FILE *buffer_tmpfile_rewind(struct line_buffer *buf); /* prepare to write. */
long buffer_tmpfile_prepare_to_read(struct line_buffer *buf);
vcs-svn: allow input errors to be detected promptly The line_buffer library silently flags input errors until buffer_deinit time; unfortunately, by that point usually errno is invalid. Expose the error flag so callers can check for and report errors early for easy debugging. some_error_prone_operation(...); if (buffer_ferror(buf)) return error("input error: %s", strerror(errno)); Signed-off-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: David Barr <david.barr@cordelta.com> Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
14 years ago
int buffer_ferror(struct line_buffer *buf);
vcs-svn: teach line_buffer to handle multiple input files Collect the line_buffer state in a newly public line_buffer struct. Callers can use multiple line_buffers to manage input from multiple files at a time. svn-fe's delta applier will use this to stream a delta from svnrdump and the preimage it applies to from fast-import at the same time. The tests don't take advantage of the new features, but I think that's okay. It is easier to find lingering examples of nonreentrant code by searching for "static" in line_buffer.c. Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
14 years ago
char *buffer_read_line(struct line_buffer *buf);
char *buffer_read_string(struct line_buffer *buf, uint32_t len);
vcs-svn: allow character-oriented input buffer_read_char can be used in place of buffer_read_string(1) to avoid consuming valuable static buffer space. The delta applier will use this to read variable-length integers one byte at a time. Underneath, it is fgetc, wrapped so the line_buffer library can maintain its role as gatekeeper of input. Later it might be worth checking if fgetc_unlocked is faster --- most line_buffer functions are not thread-safe anyway. Helpd-by: David Barr <david.barr@cordelta.com> Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
14 years ago
int buffer_read_char(struct line_buffer *buf);
vcs-svn: add binary-safe read function buffer_read_string works well for non line-oriented input except for one problem: it does not tell the caller how many bytes were actually written. This means that unless one is very careful about checking for errors (and eof) the calling program cannot tell the difference between the string "foo" followed by an early end of file and the string "foo\0bar\0baz". So introduce a variant that reports the length, too, a thinner wrapper around strbuf_fread. Its result is written to a strbuf so the caller does not need to keep track of the number of bytes read. Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
14 years ago
void buffer_read_binary(struct line_buffer *buf, struct strbuf *sb, uint32_t len);
vcs-svn: make buffer_copy_bytes return length read Currently buffer_copy_bytes does not report to its caller whether it encountered an early end of file. Add a return value representing the number of bytes read (but not the number of bytes copied). This way all three unusual conditions can be distinguished: input error with buffer_ferror, output error with ferror(outfile), early end of input by checking the return value. Signed-off-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: David Barr <david.barr@cordelta.com> Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
14 years ago
/* Returns number of bytes read (not necessarily written). */
off_t buffer_copy_bytes(struct line_buffer *buf, off_t len);
vcs-svn: make buffer_skip_bytes return length read Currently there is no way to detect when input ended if it ended early during buffer_skip_bytes. Tell the calling program how many bytes were actually skipped for easier debugging. Existing callers will still ignore early EOF. Signed-off-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: David Barr <david.barr@cordelta.com> Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
14 years ago
off_t buffer_skip_bytes(struct line_buffer *buf, off_t len);
Add stream helper library This library provides thread-unsafe fgets()- and fread()-like functions where the caller does not have to supply a buffer. It maintains a couple of static buffers and provides an API to use them. [rr: allow input from files other than stdin] [jn: with tests, documentation, and error handling improvements] Signed-off-by: David Barr <david.barr@cordelta.com> Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com> Signed-off-by: Jonathan Nieder <jrnieder@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
14 years ago
#endif