[PATCH 4/6] Add stream helper library

[Ramkumar Ramachandra <artagnon@gmail.com>]

From: David Barr <david.barr@cordelta.com>

This library provides facilities to read streams into buffers. It
maintains a couple of static buffers and provides an API to use them.

Signed-off-by: David Barr <david.barr@cordelta.com>
Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
---
 vcs-svn/line_buffer.c |  129 +++++++++++++++++++++++++++++++++++++++++++++++++
 vcs-svn/line_buffer.h |   14 +++++
 2 files changed, 143 insertions(+), 0 deletions(-)
 create mode 100644 vcs-svn/line_buffer.c
 create mode 100644 vcs-svn/line_buffer.h

diff --git a/vcs-svn/line_buffer.c b/vcs-svn/line_buffer.c
new file mode 100644
index 0000000..740676d
--- /dev/null
+++ b/vcs-svn/line_buffer.c
@@ -0,0 +1,129 @@
+#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 uint32_t line_buffer_len = 0;
+static uint32_t line_len = 0;
+static FILE *infile;
+
+int buffer_init(char *filename)
+{
+	infile = fopen(filename, "r");
+	if (!infile)
+		return 1;
+	return 0;
+}
+
+int buffer_deinit()
+{
+	fclose(infile);
+	return 0;
+}
+
+char *buffer_read_line(void)
+{
+	char *end;
+	uint32_t n_read;
+
+	if (line_len) {
+		memmove(line_buffer, &line_buffer[line_len],
+			line_buffer_len - line_len);
+		line_buffer_len -= line_len;
+		line_len = 0;
+	}
+
+	end = memchr(line_buffer, '\n', line_buffer_len);
+	while (line_buffer_len < LINE_BUFFER_LEN - 1 &&
+	       !feof(infile) && ferror(infile) && NULL == end) {
+		n_read = fread(&line_buffer[line_buffer_len], 1,
+			       LINE_BUFFER_LEN - 1 - line_buffer_len,
+			       infile);
+		end = memchr(&line_buffer[line_buffer_len], '\n', n_read);
+		line_buffer_len += n_read;
+	}
+
+	if (ferror(infile))
+		return NULL;
+
+	if (end != NULL) {
+		line_len = end - line_buffer;
+		line_buffer[line_len++] = '\0';
+	} else {
+		line_len = line_buffer_len;
+		line_buffer[line_buffer_len] = '\0';
+	}
+
+	if (line_len == 0)
+		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));
+	uint32_t offset = 0;
+	if (line_buffer_len > line_len) {
+		offset = line_buffer_len - line_len;
+		if (offset > len)
+			offset = len;
+		memcpy(s, &line_buffer[line_len], offset);
+		line_len += offset;
+	}
+	if (offset < len)
+		offset += fread(&s[offset], 1, len - offset, infile);
+	s[offset] = '\0';
+	return s;
+}
+
+void buffer_copy_bytes(uint32_t len)
+{
+	uint32_t in;
+	if (line_buffer_len > line_len) {
+		in = line_buffer_len - line_len;
+		if (in > len)
+			in = len;
+		fwrite(&line_buffer[line_len], 1, in, stdout);
+		len -= in;
+		line_len += in;
+	}
+	while (len > 0 && !feof(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);
+	}
+}
+
+void buffer_skip_bytes(uint32_t len)
+{
+	uint32_t in;
+	if (line_buffer_len > line_len) {
+		in = line_buffer_len - line_len;
+		if (in > len)
+			in = len;
+		line_len += in;
+		len -= 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..a6c42d7
--- /dev/null
+++ b/vcs-svn/line_buffer.h
@@ -0,0 +1,14 @@
+#ifndef LINE_BUFFER_H_
+#define LINE_BUFFER_H_
+
+#include <stdint.h>
+
+int buffer_init(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
-- 
1.7.1