NAME

sbuf_init, sbuf_free, sbuf_clear, sbuf_zero, sbuf_add, sbuf_add2, sbuf_trim, sbuf_detach, sbuf_extend, sbuf_sprintf, sbuf_vsprintf, sbuf_fetch, sbuf_fgets — smart buffers manipulation functions

SYNOPSIS

#include <strfunc.h>

Create, and destroy the buffer
sbuf *
sbuf_init(void);

void
sbuf_free(sbuf *sb);

Clean and truncate the buffer
int
sbuf_clear(sbuf *sb);

Just clean the buffer
int
sbuf_zero(sbuf *sb);

Add values to the end of the buffer
ssize_t
sbuf_add(sbuf *sb, conat char *string);

ssize_t
sbuf_add2(sbuf *sb, const void *data, size_t nbytes);

Trim buffer from left or right side
ssize_t
sbuf_trim(sbuf *sb, int _from_left, size_t nbytes);

Detach the buffer contents
char *
sbuf_detach(sbuf *sb, size_t *optLength, size_t *optSize);

Extend the buffer
ssize_t
sbuf_extend(sbuf *, size_t upto);

Add the formatted string
ssize_t
sbuf_sprintf(sbuf *, const char *fmt, ...);

ssize_t
sbuf_vsprintf(sbuf *, const char *fmt, va_list ap);

Get a first len characters or token
char *
sbuf_fetch(sbuf *, size_t optLen, char *optDelimiter, size_t *optRetLen, int flags);

Get a line from the stream
char *
sbuf_fgets(sbuf *, FILE *stream);

DESCRIPTION

These routines give the user a method of manipulating smart buffers. Smart buffers are used to omit headache of checking the buffer boundaries every time you're trying to add something.

Buffers may be used to handle any types of data. Internally, the buffer always contain the terminating NULL and thus significiantly simplifies the string handling.

Here is the sbuf structure (public):

typedef struct {
	char *buf;	/* The buffer data */
	size_t len;	/* Offset to end of real data (' ') */
	size_t size;	/* Allocated memory */
	size_t off;	/* Offset to start of real data */
} sbuf;

#define sbuf2ptr(sb)    ((sb)->buf + (sb)->off)
#define sbuf_len(sb)    ((sb)->len - (sb)->off) /* Meaningful length */

To create a buffer, you must invoke sbuf_init() first. After all the necessary operations, the sbuf * structure must be disposed with sbuf_free().

After the buffer is created, you might want to add a data to the buffer. It can be done using sbuf_add(sbuf *sb, const char *string) and sbuf_add2(sbuf *sb, const void *data, size_t nbytes) functions. The second function does not rely on ASCIIZ idea and places the nbytes of the data into the smart buffer. Both functions automatically extend buffer to fit all the characters provided. In case of error, the functions will return -1 and the buffer will be left intact. Upon success, sbuf_add() returns with the number of written bytes and sbuf_add2() returns with the adjusted len field of the passed sbuf * structure. Otherwise a -1 is returned by both functions.

sbuf_trim() trims given number of characters off the buffer from the left or right side, returning a number of bytes actually trimmed (which may be less than requested in case the actual buffer length is smaller). This is a zero-cost operation, as it just shifts pointers.

sbuf_detach() used to detach the buffer from the smart buffer descriptor, and return a pointer to that detached memory. If the optional optLength or optSize are given, sbuf_detach() will fill them with the actual values of the buffer length (number of meaningful bytes) and buffer size (allocated memory) appropriately. Upon detach, the smart buffer descriptor will be re-initialized to contain new, empty buffer. After detaching, the buffer descriptor (sbuf) will be reinitialized (read "empty").

To pre-extend the buffer up to the specified size, use sbuf_extend(). This function will also clear the buffer from the current position (sb->len) to the end of the allocated memory.

sbuf_sprintf() and sbuf_vsprintf() functions used to add the formatted string to the end of the buffer. These functions returns the number of bytes actually writen. Buffer will be automatically extended to fit the string. In case of error, -1 will be returned and buffer will be left intact. See the manual pages on sprintf(3) and vsprintf(3) to learn more.

sbuf_fetch() used to fetch the substring or token from the start of the buffer. If optLen argument is zero optDdelimiter must contain the set of delimiting characters, overwise ignored. The flags argument controls the behavior of splitting routinge most like in splitf(3) function, with exception that the buffer can't be split by regular expression. optRetLen will contain the length of returned string.

sbuf_fgets() is analogous to plain fgets(3), but has the significant feature. It adds the whole line from the given stream to the buffer and returns the pointer. The buffer is reallocated to suffice the memory requirements by this line.

RETURN VALUES

All functions returning ssize_t may fail with -1 and the set errno to the appropriate value.

All functions returning pointer values (sbuf *, char *) may fail with NULL and the set errno to the appropriate value.

By default, functions may not fail with ENOMEM unless the library memory control behavior was changed, see sf_mem(3).

EXAMPLE

Here is an example of creating and filling the smart buffer.

void main() {
	sbuf *sb;	/* Declare a buffer pointer */

	sb=sbuf_init();	/* Create and initialize buffer */

	/* Add some data */
	sbuf_add(sb, "one\n");
	sbuf_add2(sb, "two\n", sizeof("two\n") - 1);

	/* This will print:
	 * "one\ntwo\n"
	 */
	printf("%s", sb->buf);

	/* Add the formatted string */
	sbuf_sprintf(sb, "one: %d\n", 1);

	/* This will print:
	 * "one\ntwo\none: 1\n"
	 */
	printf("%s", sb->buf);

	/* Destroy the buffer */
	sbuf_free(sb);
};

Here is an example of reading the stream line-by-line.

void readfile(FILE *stream) {
	sbuf *sb;
	char *p;

	sb = sbuf_init();

	while((p = sbuf_fgets(sb, stream) != NULL) {
		printf("Read line: %s", p);

		/* Rewind buffer */
		sbuf_zero(sb);
	};

	sbuf_free(sb);
};

SEE ALSO

strfunc(3), splitf(3), sprintf(3), fgets(3).

AUTHORS

Lev Walkin <vlm@lionet.info>