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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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1 parent 1d73b52 commit 3bbaec00a8ffc6ea7e71c3b707851fe663d93a45 @barrbrain barrbrain committed with gitster Aug 9, 2010
Showing with 274 additions and 2 deletions.
  1. +1 −0 .gitignore
  2. +6 −2 Makefile
  3. +54 −0 t/t0080-vcs-svn.sh
  4. +46 −0 test-line-buffer.c
  5. +97 −0 vcs-svn/line_buffer.c
  6. +12 −0 vcs-svn/line_buffer.h
  7. +58 −0 vcs-svn/line_buffer.txt
View
1 .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
View
8 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)
@@ -1868,7 +1869,8 @@ xdiff-interface.o $(XDIFF_OBJS): \
xdiff/xutils.h xdiff/xprepare.h xdiff/xdiffi.h xdiff/xemit.h
$(VCSSVN_OBJS): \
- vcs-svn/obj_pool.h vcs-svn/trp.h vcs-svn/string_pool.h
+ vcs-svn/obj_pool.h vcs-svn/trp.h vcs-svn/string_pool.h \
+ vcs-svn/line_buffer.h
endif
exec_cmd.s exec_cmd.o: EXTRA_CPPFLAGS = \
@@ -2017,6 +2019,8 @@ test-date$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
View
54 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 &&
View
46 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;
+}
View
97 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();
+}
View
12 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
View
58 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.

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