line_buffer creates a couple of static buffers and expose an API for
using them. The idea is to maintain a fixed static memory pool to
avoid constant allocation and de-allocation of memory. Taken directly
from David Michael Barr's svn-dump-fast-export repository.
Signed-off-by: Ramkumar Ramachandra <artagnon@xxxxxxxxx>
---
vcs-svn/line_buffer.c | 115 +++++++++++++++++++++++++++++++++++++++++++++++++
vcs-svn/line_buffer.h | 14 ++++++
2 files changed, 129 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..6b47d38
--- /dev/null
+++ b/vcs-svn/line_buffer.c
@@ -0,0 +1,115 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "line_buffer.h"
+
+#define LINE_BUFFER_LEN 10000
+#define COPY_BUFFER_LEN 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;
+
+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(stdin) && NULL == end) {
+ n_read =
+ fread(&line_buffer[line_buffer_len], 1,
+ LINE_BUFFER_LEN - 1 - line_buffer_len,
+ stdin);
+ end = memchr(&line_buffer[line_buffer_len], '\n', n_read);
+ line_buffer_len += n_read;
+ }
+
+ if (ferror(stdin))
+ 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 = malloc(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;
+ }
+ while (offset < len && !feof(stdin)) {
+ offset += fread(&s[offset], 1, len - offset, stdin);
+ }
+ s[offset] = '\0';
+ return s;
+}
+
+void buffer_copy_bytes(uint32_t len)
+{
+ uint32_t in, out;
+ if (line_buffer_len > line_len) {
+ in = line_buffer_len - line_len;
+ if (in > len)
+ in = len;
+ out = 0;
+ while (out < in && !ferror(stdout)) {
+ out +=
+ fwrite(&line_buffer[line_len + out], 1, in - out, stdout);
+ }
+ len -= in;
+ line_len += in;
+ }
+ while (len > 0 && !feof(stdin)) {
+ in = len < COPY_BUFFER_LEN ? len : COPY_BUFFER_LEN;
+ in = fread(byte_buffer, 1, in, stdin);
+ len -= in;
+ out = 0;
+ while (out < in && !ferror(stdout)) {
+ out += fwrite(&byte_buffer[out], 1, in - out, 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(stdin)) {
+ in = len < COPY_BUFFER_LEN ? len : COPY_BUFFER_LEN;
+ in = fread(byte_buffer, 1, in, stdin);
+ len -= in;
+ }
+}
+
diff --git a/vcs-svn/line_buffer.h b/vcs-svn/line_buffer.h
new file mode 100644
index 0000000..e546f4d
--- /dev/null
+++ b/vcs-svn/line_buffer.h
@@ -0,0 +1,14 @@
+#ifndef LINE_BUFFER_H_
+#define LINE_BUFFER_H_
+
+#include <stdint.h>
+
+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);
+
+#endif
--
1.7.1
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