libbb: experimental faster string reading routines.

diff --git a/include/libbb.h b/include/libbb.h
index 671584b4349ca87c860eb1ffb6881b19318d3fc9..2bd614c7195006f9069fa795bc5f40936fe0f28a 100644 (file)
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -607,6 +607,8 @@ extern void xopen_xwrite_close(const char* file, const char *str) FAST_FUNC;
 
 /* Reads and prints to stdout till eof, then closes FILE. Exits on error: */
 extern void xprint_and_close_file(FILE *file) FAST_FUNC;
+
+extern char *bb_get_chunk_from_file(FILE *file, int *end) FAST_FUNC;
 /* Reads up to (and including) TERMINATING_STRING: */
 extern char *xmalloc_fgets_str(FILE *file, const char *terminating_string) FAST_FUNC;
 /* Chops off TERMINATING_STRING from the end: */
@@ -615,7 +617,9 @@ extern char *xmalloc_fgetline_str(FILE *file, const char *terminating_string) FA
 extern char *xmalloc_fgets(FILE *file) FAST_FUNC;
 /* Chops off '\n' from the end, unlike fgets: */
 extern char *xmalloc_fgetline(FILE *file) FAST_FUNC;
-extern char *bb_get_chunk_from_file(FILE *file, int *end) FAST_FUNC;
+/* Same, but doesn't try to conserve space (may have some slack after the end) */
+extern char *xmalloc_fgetline_fast(FILE *file) FAST_FUNC;
+
 extern void die_if_ferror(FILE *file, const char *msg) FAST_FUNC;
 extern void die_if_ferror_stdout(void) FAST_FUNC;
 extern void xfflush_stdout(void) FAST_FUNC;

diff --git a/libbb/get_line_from_file.c b/libbb/get_line_from_file.c
index 3a76f49a04f4603bd23b12732aa8abbd6f521e71..7b65ced8d3baa032d4055f6790a9724daba887b4 100644 (file)
--- a/libbb/get_line_from_file.c
+++ b/libbb/get_line_from_file.c
@@ -67,3 +67,73 @@ char* FAST_FUNC xmalloc_fgetline(FILE *file)
 
        return c;
 }
+
+/* Faster routines (~twice as fast). +170 bytes. Unused as of 2008-07.
+ *
+ * NB: they stop at NUL byte too.
+ * Performance is important here. Think "grep 50gigabyte_file"...
+ * Iironically, grep can't use it because of NUL issue.
+ * We sorely need C lib to provide fgets which reports size!
+ */
+
+static char* xmalloc_fgets_internal(FILE *file, int *sizep)
+{
+       int len;
+       int idx = 0;
+       char *linebuf = NULL;
+
+       while (1) {
+               char *r;
+
+               linebuf = xrealloc(linebuf, idx + 0x100);
+               r = fgets(&linebuf[idx], 0x100, file);
+               if (!r) {
+                       /* need to terminate in case this is error
+                        * (EOF puts NUL itself) */
+                       linebuf[idx] = '\0';
+                       break;
+               }
+               /* stupid. fgets knows the len, it should report it somehow */
+               len = strlen(&linebuf[idx]);
+               idx += len;
+               if (len != 0xff || linebuf[idx - 1] == '\n')
+                       break;
+       }
+       *sizep = idx;
+       if (idx) {
+               /* xrealloc(linebuf, idx + 1) is up to caller */
+               return linebuf;
+       }
+       free(linebuf);
+       return NULL;
+}
+
+/* Get line, remove trailing \n */
+char* FAST_FUNC xmalloc_fgetline_fast(FILE *file)
+{
+       int sz;
+       char *r = xmalloc_fgets_internal(file, &sz);
+       if (r && r[sz - 1] == '\n')
+               r[--sz] = '\0';
+       return r; /* not xrealloc(r, sz + 1)! */
+}
+
+#if 0
+char* FAST_FUNC xmalloc_fgets(FILE *file)
+{
+       int sz;
+       return xmalloc_fgets_internal(file, &sz);
+}
+
+/* Get line, remove trailing \n */
+char* FAST_FUNC xmalloc_fgetline(FILE *file)
+{
+       int sz;
+       char *r = xmalloc_fgets_internal(file, &sz);
+       if (!r)
+               return r;
+       if (r[sz - 1] == '\n')
+               r[--sz] = '\0';
+       return xrealloc(r, sz + 1);
+}
+#endif