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barrbraingitster
barrbrain
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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>
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+274
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lines changed

7 files changed

+274
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‎.gitignore‎

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@@ -166,6 +166,7 @@
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/test-dump-cache-tree
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/test-genrandom
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/test-index-version
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/test-line-buffer
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/test-match-trees
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/test-obj-pool
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/test-parse-options

‎Makefile‎

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@@ -408,6 +408,7 @@ TEST_PROGRAMS_NEED_X += test-date
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TEST_PROGRAMS_NEED_X += test-delta
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TEST_PROGRAMS_NEED_X += test-dump-cache-tree
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TEST_PROGRAMS_NEED_X += test-genrandom
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TEST_PROGRAMS_NEED_X += test-line-buffer
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TEST_PROGRAMS_NEED_X += test-match-trees
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TEST_PROGRAMS_NEED_X += test-obj-pool
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TEST_PROGRAMS_NEED_X += test-parse-options
@@ -1743,7 +1744,7 @@ ifndef NO_CURL
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endif
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XDIFF_OBJS = xdiff/xdiffi.o xdiff/xprepare.o xdiff/xutils.o xdiff/xemit.o \
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xdiff/xmerge.o xdiff/xpatience.o
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VCSSVN_OBJS = vcs-svn/string_pool.o
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VCSSVN_OBJS = vcs-svn/string_pool.o vcs-svn/line_buffer.o
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OBJECTS := $(GIT_OBJS) $(XDIFF_OBJS) $(VCSSVN_OBJS)
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dep_files := $(foreach f,$(OBJECTS),$(dir $f).depend/$(notdir $f).d)
@@ -1868,7 +1869,8 @@ xdiff-interface.o $(XDIFF_OBJS): \
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xdiff/xutils.h xdiff/xprepare.h xdiff/xdiffi.h xdiff/xemit.h
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$(VCSSVN_OBJS): \
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vcs-svn/obj_pool.h vcs-svn/trp.h vcs-svn/string_pool.h
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vcs-svn/obj_pool.h vcs-svn/trp.h vcs-svn/string_pool.h \
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vcs-svn/line_buffer.h
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endif
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exec_cmd.s exec_cmd.o: EXTRA_CPPFLAGS = \
@@ -2017,6 +2019,8 @@ test-date$X: date.o ctype.o
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test-delta$X: diff-delta.o patch-delta.o
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test-line-buffer$X: vcs-svn/lib.a
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test-parse-options$X: parse-options.o
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test-string-pool$X: vcs-svn/lib.a

‎t/t0080-vcs-svn.sh‎

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@@ -76,6 +76,60 @@ test_expect_success 'obj pool: high-water mark' '
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test_cmp expected actual
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'
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test_expect_success 'line buffer' '
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echo HELLO >expected1 &&
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printf "%s\n" "" HELLO >expected2 &&
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echo >expected3 &&
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printf "%s\n" "" Q | q_to_nul >expected4 &&
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printf "%s\n" foo "" >expected5 &&
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printf "%s\n" "" foo >expected6 &&
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test-line-buffer <<-\EOF >actual1 &&
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5
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HELLO
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EOF
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test-line-buffer <<-\EOF >actual2 &&
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0
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5
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HELLO
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EOF
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q_to_nul <<-\EOF |
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1
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Q
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EOF
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test-line-buffer >actual3 &&
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q_to_nul <<-\EOF |
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0
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1
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Q
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EOF
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test-line-buffer >actual4 &&
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test-line-buffer <<-\EOF >actual5 &&
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5
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foo
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EOF
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test-line-buffer <<-\EOF >actual6 &&
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0
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5
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foo
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EOF
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test_cmp expected1 actual1 &&
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test_cmp expected2 actual2 &&
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test_cmp expected3 actual3 &&
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test_cmp expected4 actual4 &&
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test_cmp expected5 actual5 &&
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test_cmp expected6 actual6
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'
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test_expect_success 'string pool' '
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echo a does not equal b >expected.differ &&
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echo a equals a >expected.match &&

‎test-line-buffer.c‎

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/*
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* test-line-buffer.c: code to exercise the svn importer's input helper
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*
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* Input format:
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* number NL
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* (number bytes) NL
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* number NL
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* ...
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*/
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#include "git-compat-util.h"
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#include "vcs-svn/line_buffer.h"
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static uint32_t strtouint32(const char *s)
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{
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char *end;
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uintmax_t n = strtoumax(s, &end, 10);
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if (*s == '\0' || *end != '\0')
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die("invalid count: %s", s);
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return (uint32_t) n;
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}
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int main(int argc, char *argv[])
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{
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char *s;
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if (argc != 1)
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usage("test-line-buffer < input.txt");
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if (buffer_init(NULL))
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die_errno("open error");
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while ((s = buffer_read_line())) {
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s = buffer_read_string(strtouint32(s));
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fputs(s, stdout);
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fputc('\n', stdout);
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buffer_skip_bytes(1);
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if (!(s = buffer_read_line()))
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break;
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buffer_copy_bytes(strtouint32(s) + 1);
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}
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if (buffer_deinit())
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die("input error");
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if (ferror(stdout))
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die("output error");
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buffer_reset();
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return 0;
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}

‎vcs-svn/line_buffer.c‎

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/*
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* Licensed under a two-clause BSD-style license.
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* See LICENSE for details.
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*/
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#include "git-compat-util.h"
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#include "line_buffer.h"
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#include "obj_pool.h"
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#define LINE_BUFFER_LEN 10000
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#define COPY_BUFFER_LEN 4096
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/* Create memory pool for char sequence of known length */
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obj_pool_gen(blob, char, 4096)
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static char line_buffer[LINE_BUFFER_LEN];
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static char byte_buffer[COPY_BUFFER_LEN];
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static FILE *infile;
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int buffer_init(const char *filename)
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{
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infile = filename ? fopen(filename, "r") : stdin;
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if (!infile)
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return -1;
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return 0;
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}
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int buffer_deinit(void)
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{
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int err;
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if (infile == stdin)
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return ferror(infile);
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err = ferror(infile);
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err |= fclose(infile);
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return err;
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}
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/* Read a line without trailing newline. */
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char *buffer_read_line(void)
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{
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char *end;
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if (!fgets(line_buffer, sizeof(line_buffer), infile))
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/* Error or data exhausted. */
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return NULL;
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end = line_buffer + strlen(line_buffer);
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if (end[-1] == '\n')
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end[-1] = '\0';
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else if (feof(infile))
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; /* No newline at end of file. That's fine. */
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else
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/*
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* Line was too long.
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* There is probably a saner way to deal with this,
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* but for now let's return an error.
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*/
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return NULL;
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return line_buffer;
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}
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char *buffer_read_string(uint32_t len)
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{
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char *s;
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blob_free(blob_pool.size);
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s = blob_pointer(blob_alloc(len + 1));
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s[fread(s, 1, len, infile)] = '\0';
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return ferror(infile) ? NULL : s;
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}
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void buffer_copy_bytes(uint32_t len)
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{
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uint32_t in;
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while (len > 0 && !feof(infile) && !ferror(infile)) {
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in = len < COPY_BUFFER_LEN ? len : COPY_BUFFER_LEN;
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in = fread(byte_buffer, 1, in, infile);
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len -= in;
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fwrite(byte_buffer, 1, in, stdout);
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if (ferror(stdout)) {
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buffer_skip_bytes(len);
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return;
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}
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}
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}
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void buffer_skip_bytes(uint32_t len)
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{
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uint32_t in;
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while (len > 0 && !feof(infile) && !ferror(infile)) {
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in = len < COPY_BUFFER_LEN ? len : COPY_BUFFER_LEN;
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in = fread(byte_buffer, 1, in, infile);
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len -= in;
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}
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}
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void buffer_reset(void)
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{
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blob_reset();
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}

‎vcs-svn/line_buffer.h‎

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#ifndef LINE_BUFFER_H_
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#define LINE_BUFFER_H_
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int buffer_init(const char *filename);
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int buffer_deinit(void);
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char *buffer_read_line(void);
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char *buffer_read_string(uint32_t len);
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void buffer_copy_bytes(uint32_t len);
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void buffer_skip_bytes(uint32_t len);
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void buffer_reset(void);
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#endif

‎vcs-svn/line_buffer.txt‎

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line_buffer API
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===============
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The line_buffer library provides a convenient interface for
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mostly-line-oriented input.
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Each line is not permitted to exceed 10000 bytes. The provided
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functions are not thread-safe or async-signal-safe, and like
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`fgets()`, they generally do not function correctly if interrupted
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by a signal without SA_RESTART set.
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Calling sequence
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----------------
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The calling program:
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- specifies a file to read with `buffer_init`
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- processes input with `buffer_read_line`, `buffer_read_string`,
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`buffer_skip_bytes`, and `buffer_copy_bytes`
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- closes the file with `buffer_deinit`, perhaps to start over and
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read another file.
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Before exiting, the caller can use `buffer_reset` to deallocate
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resources for the benefit of profiling tools.
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Functions
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---------
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`buffer_init`::
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Open the named file for input. If filename is NULL,
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start reading from stdin. On failure, returns -1 (with
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errno indicating the nature of the failure).
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`buffer_deinit`::
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Stop reading from the current file (closing it unless
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it was stdin). Returns nonzero if `fclose` fails or
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the error indicator was set.
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`buffer_read_line`::
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Read a line and strip off the trailing newline.
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On failure or end of file, returns NULL.
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`buffer_read_string`::
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Read `len` characters of input or up to the end of the
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file, whichever comes first. Returns NULL on error.
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Returns whatever characters were read (possibly "")
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for end of file.
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`buffer_copy_bytes`::
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Read `len` bytes of input and dump them to the standard output
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stream. Returns early for error or end of file.
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`buffer_skip_bytes`::
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Discards `len` bytes from the input stream (stopping early
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if necessary because of an error or eof).
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`buffer_reset`::
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Deallocates non-static buffers.

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