[PATCH 06/10] Add stream helper library
- From
Jonathan Nieder <jrnieder@gmail.com>
- Date
- Aug 9, 2010, 22:39 UTC
- Message-ID
- <20100809223943.GB4429@burratino>
- In-Reply-To
- <20100809215719.GA4203@burratino>
From: David Barr <david.barr@cordelta.com>
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> --- New tests and API docs. The return value from buffer_deinit can be used to check for errors now (I found this useful when writing tests).
.gitignore | 1 + Makefile | 8 +++- t/t0080-vcs-svn.sh | 54 ++++++++++++++++++++++++++ test-line-buffer.c | 46 ++++++++++++++++++++++ vcs-svn/line_buffer.c | 97 +++++++++++++++++++++++++++++++++++++++++++++++ vcs-svn/line_buffer.h | 12 ++++++ vcs-svn/line_buffer.txt | 58 ++++++++++++++++++++++++++++ 7 files changed, 274 insertions(+), 2 deletions(-) create mode 100644 test-line-buffer.c create mode 100644 vcs-svn/line_buffer.c create mode 100644 vcs-svn/line_buffer.h create mode 100644 vcs-svn/line_buffer.txt
diff --git a/.gitignore b/.gitignore index 9f109db..8c0512e 100644 --- a/.gitignore +++ b/.gitignore @@ -166,6 +166,7 @@ /test-dump-cache-tree /test-genrandom /test-index-version +/test-line-buffer /test-match-trees /test-obj-pool /test-parse-options diff --git a/Makefile b/Makefile index 24103c9..a76cce5 100644 --- a/Makefile +++ b/Makefile @@ -408,6 +408,7 @@ TEST_PROGRAMS_NEED_X += test-date TEST_PROGRAMS_NEED_X += test-delta TEST_PROGRAMS_NEED_X += test-dump-cache-tree TEST_PROGRAMS_NEED_X += test-genrandom +TEST_PROGRAMS_NEED_X += test-line-buffer TEST_PROGRAMS_NEED_X += test-match-trees TEST_PROGRAMS_NEED_X += test-obj-pool TEST_PROGRAMS_NEED_X += test-parse-options @@ -1743,7 +1744,7 @@ ifndef NO_CURL endif XDIFF_OBJS = xdiff/xdiffi.o xdiff/xprepare.o xdiff/xutils.o xdiff/xemit.o \ xdiff/xmerge.o xdiff/xpatience.o -VCSSVN_OBJS = vcs-svn/string_pool.o +VCSSVN_OBJS = vcs-svn/string_pool.o vcs-svn/line_buffer.o OBJECTS := $(GIT_OBJS) $(XDIFF_OBJS) $(VCSSVN_OBJS) dep_files := $(foreach f,$(OBJECTS),$(dir $f).depend/$(notdir $f).d) @@ -1867,7 +1868,8 @@ xdiff-interface.o $(XDIFF_OBJS): \ xdiff/xutils.h xdiff/xprepare.h xdiff/xdiffi.h xdiff/xemit.h $(VCSSVN_OBJS): \ - vcs-svn/obj_pool.h vcs-svn/trp.h vcs-svn/string_pool.h + vcs-svn/obj_pool.h vcs-svn/trp.h vcs-svn/string_pool.h \ + vcs-svn/line_buffer.h endif exec_cmd.s exec_cmd.o: EXTRA_CPPFLAGS = \ @@ -2016,6 +2018,8 @@ test-date$X: date.o ctype.o test-delta$X: diff-delta.o patch-delta.o +test-line-buffer$X: vcs-svn/lib.a + test-parse-options$X: parse-options.o test-string-pool$X: vcs-svn/lib.a diff --git a/t/t0080-vcs-svn.sh b/t/t0080-vcs-svn.sh index 99a314b..d3225ad 100755 --- a/t/t0080-vcs-svn.sh +++ b/t/t0080-vcs-svn.sh @@ -76,6 +76,60 @@ test_expect_success 'obj pool: high-water mark' ' test_cmp expected actual ' +test_expect_success 'line buffer' ' + echo HELLO >expected1 && + printf "%s\n" "" HELLO >expected2 && + echo >expected3 && + printf "%s\n" "" Q | q_to_nul >expected4 && + printf "%s\n" foo "" >expected5 && + printf "%s\n" "" foo >expected6 && + + test-line-buffer <<-\EOF >actual1 && + 5 + HELLO + EOF + + test-line-buffer <<-\EOF >actual2 && + 0 + + 5 + HELLO + EOF + + q_to_nul <<-\EOF | + 1 + Q + EOF + test-line-buffer >actual3 && + + q_to_nul <<-\EOF | + 0 + + 1 + Q + EOF + test-line-buffer >actual4 && + + test-line-buffer <<-\EOF >actual5 && + 5 + foo + EOF + + test-line-buffer <<-\EOF >actual6 && + 0 + + 5 + foo + EOF + + test_cmp expected1 actual1 && + test_cmp expected2 actual2 && + test_cmp expected3 actual3 && + test_cmp expected4 actual4 && + test_cmp expected5 actual5 && + test_cmp expected6 actual6 +' + test_expect_success 'string pool' ' echo a does not equal b >expected.differ && echo a equals a >expected.match && diff --git a/test-line-buffer.c b/test-line-buffer.c new file mode 100644 index 0000000..c11bf7f --- /dev/null +++ b/test-line-buffer.c @@ -0,0 +1,46 @@ +/* + * test-line-buffer.c: code to exercise the svn importer's input helper + * + * Input format: + * number NL + * (number bytes) NL + * number NL + * ... + */ + +#include "git-compat-util.h" +#include "vcs-svn/line_buffer.h" + +static uint32_t strtouint32(const char *s) +{ + char *end; + uintmax_t n = strtoumax(s, &end, 10); + if (*s == '\0' || *end != '\0') + die("invalid count: %s", s); + return (uint32_t) n; +} + +int main(int argc, char *argv[]) +{ + char *s; + + if (argc != 1) + usage("test-line-buffer < input.txt"); + if (buffer_init(NULL)) + die_errno("open error"); + while ((s = buffer_read_line())) { + s = buffer_read_string(strtouint32(s)); + fputs(s, stdout); + fputc('\n', stdout); + buffer_skip_bytes(1); + if (!(s = buffer_read_line())) + break; + buffer_copy_bytes(strtouint32(s) + 1); + } + if (buffer_deinit()) + die("input error"); + if (ferror(stdout)) + die("output error"); + buffer_reset(); + return 0; +} diff --git a/vcs-svn/line_buffer.c b/vcs-svn/line_buffer.c new file mode 100644 index 0000000..1543567 --- /dev/null +++ b/vcs-svn/line_buffer.c @@ -0,0 +1,97 @@ +/* + * Licensed under a two-clause BSD-style license. + * See LICENSE for details. + */ + +#include "git-compat-util.h" +#include "line_buffer.h" +#include "obj_pool.h" + +#define LINE_BUFFER_LEN 10000 +#define COPY_BUFFER_LEN 4096 + +/* Create memory pool for char sequence of known length */ +obj_pool_gen(blob, char, 4096) + +static char line_buffer[LINE_BUFFER_LEN]; +static char byte_buffer[COPY_BUFFER_LEN]; +static FILE *infile; + +int buffer_init(const char *filename) +{ + infile = filename ? fopen(filename, "r") : stdin; + if (!infile) + return -1; + return 0; +} + +int buffer_deinit(void) +{ + int err; + if (infile == stdin) + return ferror(infile); + err = ferror(infile); + err |= fclose(infile); + return err; +} + +/* Read a line without trailing newline. */ +char *buffer_read_line(void) +{ + char *end; + if (!fgets(line_buffer, sizeof(line_buffer), infile)) + /* Error or data exhausted. */ + return NULL; + end = line_buffer + strlen(line_buffer); + if (end[-1] == '\n') + end[-1] = '\0'; + else if (feof(infile)) + ; /* No newline at end of file. That's fine. */ + else + /* + * Line was too long. + * There is probably a saner way to deal with this, + * but for now let's return an error. + */ + return NULL; + return line_buffer; +} + +char *buffer_read_string(uint32_t len) +{ + char *s; + blob_free(blob_pool.size); + s = blob_pointer(blob_alloc(len + 1)); + s[fread(s, 1, len, infile)] = '\0'; + return ferror(infile) ? NULL : s; +} + +void buffer_copy_bytes(uint32_t len) +{ + uint32_t in; + while (len > 0 && !feof(infile) && !ferror(infile)) { + in = len < COPY_BUFFER_LEN ? len : COPY_BUFFER_LEN; + in = fread(byte_buffer, 1, in, infile); + len -= in; + fwrite(byte_buffer, 1, in, stdout); + if (ferror(stdout)) { + buffer_skip_bytes(len); + return; + } + } +} + +void buffer_skip_bytes(uint32_t len) +{ + uint32_t in; + while (len > 0 && !feof(infile) && !ferror(infile)) { + in = len < COPY_BUFFER_LEN ? len : COPY_BUFFER_LEN; + in = fread(byte_buffer, 1, in, infile); + len -= in; + } +} + +void buffer_reset(void) +{ + blob_reset(); +} diff --git a/vcs-svn/line_buffer.h b/vcs-svn/line_buffer.h new file mode 100644 index 0000000..9c78ae1 --- /dev/null +++ b/vcs-svn/line_buffer.h @@ -0,0 +1,12 @@ +#ifndef LINE_BUFFER_H_ +#define LINE_BUFFER_H_ + +int buffer_init(const char *filename); +int buffer_deinit(void); +char *buffer_read_line(void); +char *buffer_read_string(uint32_t len); +void buffer_copy_bytes(uint32_t len); +void buffer_skip_bytes(uint32_t len); +void buffer_reset(void); + +#endif diff --git a/vcs-svn/line_buffer.txt b/vcs-svn/line_buffer.txt new file mode 100644 index 0000000..8906fb1 --- /dev/null +++ b/vcs-svn/line_buffer.txt @@ -0,0 +1,58 @@ +line_buffer API +=============== + +The line_buffer library provides a convenient interface for +mostly-line-oriented input. + +Each line is not permitted to exceed 10000 bytes. The provided +functions are not thread-safe or async-signal-safe, and like +`fgets()`, they generally do not function correctly if interrupted +by a signal without SA_RESTART set. + +Calling sequence +---------------- + +The calling program: + + - specifies a file to read with `buffer_init` + - processes input with `buffer_read_line`, `buffer_read_string`, + `buffer_skip_bytes`, and `buffer_copy_bytes` + - closes the file with `buffer_deinit`, perhaps to start over and + read another file. + +Before exiting, the caller can use `buffer_reset` to deallocate +resources for the benefit of profiling tools. + +Functions +--------- + +`buffer_init`:: + Open the named file for input. If filename is NULL, + start reading from stdin. On failure, returns -1 (with + errno indicating the nature of the failure). + +`buffer_deinit`:: + Stop reading from the current file (closing it unless + it was stdin). Returns nonzero if `fclose` fails or + the error indicator was set. + +`buffer_read_line`:: + Read a line and strip off the trailing newline. + On failure or end of file, returns NULL. + +`buffer_read_string`:: + Read `len` characters of input or up to the end of the + file, whichever comes first. Returns NULL on error. + Returns whatever characters were read (possibly "") + for end of file. + +`buffer_copy_bytes`:: + Read `len` bytes of input and dump them to the standard output + stream. Returns early for error or end of file. + +`buffer_skip_bytes`:: + Discards `len` bytes from the input stream (stopping early + if necessary because of an error or eof). + +`buffer_reset`:: + Deallocates non-static buffers.
-- 1.7.2.1.544.ga752d.dirty