Adding upstream version 3.8.5.upstream/3.8.5

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 719 insertions, 0 deletions

diff --git a/src/util/vstring.c b/src/util/vstring.c
new file mode 100644
index 0000000..43897eb
--- /dev/null
+++ b/src/util/vstring.c
@@ -0,0 +1,719 @@
+/*++
+/* NAME
+/*	vstring 3
+/* SUMMARY
+/*	arbitrary-length string manager
+/* SYNOPSIS
+/*	#include <vstring.h>
+/*
+/*	VSTRING	*vstring_alloc(len)
+/*	ssize_t	len;
+/*
+/*	vstring_ctl(vp, type, value, ..., VSTRING_CTL_END)
+/*	VSTRING	*vp;
+/*	int	type;
+/*
+/*	VSTRING	*vstring_free(vp)
+/*	VSTRING	*vp;
+/*
+/*	char	*vstring_str(vp)
+/*	VSTRING	*vp;
+/*
+/*	ssize_t	VSTRING_LEN(vp)
+/*	VSTRING	*vp;
+/*
+/*	char	*vstring_end(vp)
+/*	VSTRING	*vp;
+/*
+/*	void	VSTRING_ADDCH(vp, ch)
+/*	VSTRING	*vp;
+/*	int	ch;
+/*
+/*	int	VSTRING_SPACE(vp, len)
+/*	VSTRING	*vp;
+/*	ssize_t	len;
+/*
+/*	ssize_t	vstring_avail(vp)
+/*	VSTRING	*vp;
+/*
+/*	VSTRING	*vstring_truncate(vp, len)
+/*	VSTRING	*vp;
+/*	ssize_t	len;
+/*
+/*	VSTRING	*vstring_set_payload_size(vp, len)
+/*	VSTRING	*vp;
+/*	ssize_t	len;
+/*
+/*	void	VSTRING_RESET(vp)
+/*	VSTRING	*vp;
+/*
+/*	void	VSTRING_TERMINATE(vp)
+/*	VSTRING	*vp;
+/*
+/*	void	VSTRING_SKIP(vp)
+/*	VSTRING	*vp;
+/*
+/*	VSTRING	*vstring_strcpy(vp, src)
+/*	VSTRING	*vp;
+/*	const char *src;
+/*
+/*	VSTRING	*vstring_strncpy(vp, src, len)
+/*	VSTRING	*vp;
+/*	const char *src;
+/*	ssize_t	len;
+/*
+/*	VSTRING	*vstring_strcat(vp, src)
+/*	VSTRING	*vp;
+/*	const char *src;
+/*
+/*	VSTRING	*vstring_strncat(vp, src, len)
+/*	VSTRING	*vp;
+/*	const char *src;
+/*	ssize_t	len;
+/*
+/*	VSTRING	*vstring_memcpy(vp, src, len)
+/*	VSTRING	*vp;
+/*	const char *src;
+/*	ssize_t	len;
+/*
+/*	VSTRING	*vstring_memcat(vp, src, len)
+/*	VSTRING	*vp;
+/*	const char *src;
+/*	ssize_t	len;
+/*
+/*	char	*vstring_memchr(vp, ch)
+/*	VSTRING	*vp;
+/*	int	ch;
+/*
+/*	VSTRING	*vstring_insert(vp, start, src, len)
+/*	VSTRING	*vp;
+/*	ssize_t	start;
+/*	const char *src;
+/*	ssize_t	len;
+/*
+/*	VSTRING	*vstring_prepend(vp, src, len)
+/*	VSTRING	*vp;
+/*	const char *src;
+/*	ssize_t	len;
+/*
+/*	VSTRING	*vstring_sprintf(vp, format, ...)
+/*	VSTRING	*vp;
+/*	const char *format;
+/*
+/*	VSTRING	*vstring_sprintf_append(vp, format, ...)
+/*	VSTRING	*vp;
+/*	const char *format;
+/*
+/*	VSTRING	*vstring_sprintf_prepend(vp, format, ...)
+/*	VSTRING	*vp;
+/*	const char *format;
+/*
+/*	VSTRING	*vstring_vsprintf(vp, format, ap)
+/*	VSTRING	*vp;
+/*	const char *format;
+/*	va_list	ap;
+/*
+/*	VSTRING	*vstring_vsprintf_append(vp, format, ap)
+/*	VSTRING	*vp;
+/*	const char *format;
+/*	va_list	ap;
+/* AUXILIARY FUNCTIONS
+/*	char	*vstring_export(vp)
+/*	VSTRING	*vp;
+/*
+/*	VSTRING	*vstring_import(str)
+/*	char	*str;
+/* DESCRIPTION
+/*	The functions and macros in this module implement arbitrary-length
+/*	strings and common operations on those strings. The strings do not
+/*	need to be null terminated and may contain arbitrary binary data.
+/*	The strings manage their own memory and grow automatically when full.
+/*	The optional string null terminator does not add to the string length.
+/*
+/*	vstring_alloc() allocates storage for a variable-length string
+/*	of at least "len" bytes. The minimal length is 1. The result
+/*	is a null-terminated string of length zero.
+/*
+/*	vstring_ctl() gives additional control over VSTRING behavior.
+/*	The function takes a VSTRING pointer and a list of zero or
+/*	more macros with zer or more arguments, terminated with
+/*	CA_VSTRING_CTL_END which has none.
+/* .IP "CA_VSTRING_CTL_MAXLEN(ssize_t len)"
+/*	Specifies a hard upper limit on a string's length. When the
+/*	length would be exceeded, the program simulates a memory
+/*	allocation problem (i.e. it terminates through msg_fatal()).
+/*	This functionality is currently unimplemented.
+/* .IP "CA_VSTRING_CTL_EXACT (no argument)"
+/*	Allocate the requested amounts, instead of rounding up.
+/*	This should be used for tests only.
+/* .IP "CA_VSTRING_CTL_END (no argument)"
+/*	Specifies the end of the argument list. Forgetting to terminate
+/*	the argument list may cause the program to crash.
+/* .PP
+/*	VSTRING_SPACE() ensures that the named string has room for
+/*	"len" more characters. VSTRING_SPACE() is an unsafe macro
+/*	that either returns zero or never returns.
+/*
+/*	vstring_avail() returns the number of bytes that can be placed
+/*	into the buffer before the buffer would need to grow.
+/*
+/*	vstring_free() reclaims storage for a variable-length string.
+/*	It conveniently returns a null pointer.
+/*
+/*	vstring_str() is a macro that returns the string value
+/*	of a variable-length string. It is a safe macro that
+/*	evaluates its argument only once.
+/*
+/*	VSTRING_LEN() is a macro that returns the current length of
+/*	its argument (i.e. the distance from the start of the string
+/*	to the current write position). VSTRING_LEN() is an unsafe macro
+/*	that evaluates its argument more than once.
+/*
+/*	vstring_end() is a macro that returns the current write position of
+/*	its argument. It is a safe macro that evaluates its argument only once.
+/*
+/*	VSTRING_ADDCH() adds a character to a variable-length string
+/*	and extends the string if it fills up.  \fIvs\fP is a pointer
+/*	to a VSTRING structure; \fIch\fP the character value to be written.
+/*	The result is the written character.
+/*	Note that VSTRING_ADDCH() is an unsafe macro that evaluates some
+/*	arguments more than once. The result is NOT null-terminated.
+/*
+/*	vstring_truncate() truncates the named string to the specified
+/*	length. If length is negative, the trailing portion is kept.
+/*	The operation has no effect when the string is shorter.
+/*	The string is not null-terminated.
+/*
+/*	vstring_set_payload_size() sets the number of 'used' bytes
+/*	in the named buffer's metadata. This determines the buffer
+/*	write position and the VSTRING_LEN() result. The payload
+/*	size must be within the closed range [0, number of allocated
+/*	bytes]. The typical usage is to request buffer space with
+/*	VSTRING_SPACE(), to use some non-VSTRING operations to write
+/*	to the buffer, and to call vstring_set_payload_size() to
+/*	update buffer metadata, perhaps followed by VSTRING_TERMINATE().
+/*
+/*	VSTRING_RESET() is a macro that resets the write position of its
+/*	string argument to the very beginning. Note that VSTRING_RESET()
+/*	is an unsafe macro that evaluates some arguments more than once.
+/*	The result is NOT null-terminated.
+/*
+/*	VSTRING_TERMINATE() null-terminates its string argument.
+/*	VSTRING_TERMINATE() is an unsafe macro that evaluates some
+/*	arguments more than once.
+/*	VSTRING_TERMINATE() does not return an interesting result.
+/*
+/*	VSTRING_SKIP() is a macro that moves the write position to the first
+/*	null byte after the current write position. VSTRING_SKIP() is an unsafe
+/*	macro that evaluates some arguments more than once.
+/*
+/*	vstring_strcpy() copies a null-terminated string to a variable-length
+/*	string. \fIsrc\fP provides the data to be copied; \fIvp\fP is the
+/*	target and result value.  The result is null-terminated.
+/*
+/*	vstring_strncpy() copies at most \fIlen\fR characters. Otherwise it is
+/*	identical to vstring_strcpy().
+/*
+/*	vstring_strcat() appends a null-terminated string to a variable-length
+/*	string. \fIsrc\fP provides the data to be copied; \fIvp\fP is the
+/*	target and result value.  The result is null-terminated.
+/*
+/*	vstring_strncat() copies at most \fIlen\fR characters. Otherwise it is
+/*	identical to vstring_strcat().
+/*
+/*	vstring_memcpy() copies \fIlen\fR bytes to a variable-length string.
+/*	\fIsrc\fP provides the data to be copied; \fIvp\fP is the
+/*	target and result value.  The result is not null-terminated.
+/*
+/*	vstring_memcat() appends \fIlen\fR bytes to a variable-length string.
+/*	\fIsrc\fP provides the data to be copied; \fIvp\fP is the
+/*	target and result value.  The result is not null-terminated.
+/*
+/*	vstring_memchr() locates a byte in a variable-length string.
+/*
+/*	vstring_insert() inserts a buffer content into a variable-length
+/*	string at the specified start position. The result is
+/*	null-terminated.
+/*
+/*	vstring_prepend() prepends a buffer content to a variable-length
+/*	string. The result is null-terminated.
+/*
+/*	vstring_sprintf() produces a formatted string according to its
+/*	\fIformat\fR argument. See vstring_vsprintf() for details.
+/*
+/*	vstring_sprintf_append() is like vstring_sprintf(), but appends
+/*	to the end of the result buffer.
+/*
+/*	vstring_sprintf_append() is like vstring_sprintf(), but prepends
+/*	to the beginning of the result buffer.
+/*
+/*	vstring_vsprintf() returns a null-terminated string according to
+/*	the \fIformat\fR argument. It understands the s, c, d, u,
+/*	o, x, X, p, e, f and g format types, the l modifier, field width
+/*	and precision, sign, and null or space padding. This module
+/*	can format strings as large as available memory permits.
+/*
+/*	vstring_vsprintf_append() is like vstring_vsprintf(), but appends
+/*	to the end of the result buffer.
+/*
+/*	In addition to stdio-like format specifiers, vstring_vsprintf()
+/*	recognizes %m and expands it to the corresponding errno text.
+/*
+/*	vstring_export() extracts the string value from a VSTRING.
+/*	The VSTRING is destroyed. The result should be passed to myfree().
+/*
+/*	vstring_import() takes a `bare' string and converts it to
+/*	a VSTRING. The string argument must be obtained from mymalloc().
+/*	The string argument is not copied.
+/* DIAGNOSTICS
+/*	Fatal errors: memory allocation failure.
+/* BUGS
+/*	Auto-resizing may change the address of the string data in
+/*	a vstring structure. Beware of dangling pointers.
+/* HISTORY
+/* .ad
+/* .fi
+/*	A vstring module appears in the UNPROTO software by Wietse Venema.
+/* AUTHOR(S)
+/*	Wietse Venema
+/*	IBM T.J. Watson Research
+/*	P.O. Box 704
+/*	Yorktown Heights, NY 10598, USA
+/*
+/*	Wietse Venema
+/*	Google, Inc.
+/*	111 8th Avenue
+/*	New York, NY 10011, USA
+/*--*/
+
+/* System libraries. */
+
+#include <sys_defs.h>
+#include <stddef.h>
+#include <stdlib.h>			/* 44BSD stdarg.h uses abort() */
+#include <stdarg.h>
+#include <string.h>
+
+/* Utility library. */
+
+#define VSTRING_INTERNAL
+
+#include "mymalloc.h"
+#include "msg.h"
+#include "vbuf_print.h"
+#include "vstring.h"
+
+/* vstring_extend - variable-length string buffer extension policy */
+
+static void vstring_extend(VBUF *bp, ssize_t incr)
+{
+    size_t  used = bp->ptr - bp->data;
+    ssize_t new_len;
+
+    /*
+     * Note: vp->vbuf.len is the current buffer size (both on entry and on
+     * exit of this routine). We round up the increment size to the buffer
+     * size to avoid silly little buffer increments. With really large
+     * strings we might want to abandon the length doubling strategy, and go
+     * to fixed increments.
+     * 
+     * The length overflow tests here and in vstring_alloc() should protect us
+     * against all length overflow problems within vstring library routines.
+     * 
+     * Safety net: add a gratuitous null terminator so that C-style string
+     * operations won't scribble past the end.
+     */
+    if ((bp->flags & VSTRING_FLAG_EXACT) == 0 && bp->len > incr)
+	incr = bp->len;
+    if (bp->len > SSIZE_T_MAX - incr - 1)
+	msg_fatal("vstring_extend: length overflow");
+    new_len = bp->len + incr;
+    bp->data = (unsigned char *) myrealloc((void *) bp->data, new_len + 1);
+    bp->data[new_len] = 0;
+    bp->len = new_len;
+    bp->ptr = bp->data + used;
+    bp->cnt = bp->len - used;
+}
+
+/* vstring_buf_get_ready - vbuf callback for read buffer empty condition */
+
+static int vstring_buf_get_ready(VBUF *unused_buf)
+{
+    return (VBUF_EOF);			/* be VSTREAM-friendly */
+}
+
+/* vstring_buf_put_ready - vbuf callback for write buffer full condition */
+
+static int vstring_buf_put_ready(VBUF *bp)
+{
+    vstring_extend(bp, 1);
+    return (0);
+}
+
+/* vstring_buf_space - vbuf callback to reserve space */
+
+static int vstring_buf_space(VBUF *bp, ssize_t len)
+{
+    ssize_t need;
+
+    if (len < 0)
+	msg_panic("vstring_buf_space: bad length %ld", (long) len);
+    if ((need = len - bp->cnt) > 0)
+	vstring_extend(bp, need);
+    return (0);
+}
+
+/* vstring_alloc - create variable-length string */
+
+VSTRING *vstring_alloc(ssize_t len)
+{
+    VSTRING *vp;
+
+    /*
+     * Safety net: add a gratuitous null terminator so that C-style string
+     * operations won't scribble past the end.
+     */
+    if (len < 1 || len > SSIZE_T_MAX - 1)
+	msg_panic("vstring_alloc: bad length %ld", (long) len);
+    vp = (VSTRING *) mymalloc(sizeof(*vp));
+    vp->vbuf.flags = 0;
+    vp->vbuf.len = 0;
+    vp->vbuf.data = (unsigned char *) mymalloc(len + 1);
+    vp->vbuf.data[len] = 0;
+    vp->vbuf.len = len;
+    VSTRING_RESET(vp);
+    vp->vbuf.data[0] = 0;
+    vp->vbuf.get_ready = vstring_buf_get_ready;
+    vp->vbuf.put_ready = vstring_buf_put_ready;
+    vp->vbuf.space = vstring_buf_space;
+    return (vp);
+}
+
+/* vstring_free - destroy variable-length string */
+
+VSTRING *vstring_free(VSTRING *vp)
+{
+    if (vp->vbuf.data)
+	myfree((void *) vp->vbuf.data);
+    myfree((void *) vp);
+    return (0);
+}
+
+/* vstring_ctl - modify memory management policy */
+
+void    vstring_ctl(VSTRING *vp,...)
+{
+    va_list ap;
+    int     code;
+
+    va_start(ap, vp);
+    while ((code = va_arg(ap, int)) != VSTRING_CTL_END) {
+	switch (code) {
+	default:
+	    msg_panic("vstring_ctl: unknown code: %d", code);
+	case VSTRING_CTL_EXACT:
+	    vp->vbuf.flags |= VSTRING_FLAG_EXACT;
+	    break;
+	}
+    }
+    va_end(ap);
+}
+
+/* vstring_truncate - truncate string */
+
+VSTRING *vstring_truncate(VSTRING *vp, ssize_t len)
+{
+    ssize_t move;
+
+    if (len < 0) {
+	len = (-len);
+	if ((move = VSTRING_LEN(vp) - len) > 0)
+	    memmove(vstring_str(vp), vstring_str(vp) + move, len);
+    }
+    if (len < VSTRING_LEN(vp))
+	VSTRING_AT_OFFSET(vp, len);
+    return (vp);
+}
+
+/* vstring_set_payload_size - public version of VSTRING_AT_OFFSET */
+
+VSTRING *vstring_set_payload_size(VSTRING *vp, ssize_t len)
+{
+    if (len < 0 || len > vp->vbuf.len)
+	msg_panic("vstring_set_payload_size: invalid offset: %ld", (long) len);
+    if (vp->vbuf.data[vp->vbuf.len] != 0)
+	msg_panic("vstring_set_payload_size: no safety null byte");
+    VSTRING_AT_OFFSET(vp, len);
+    return (vp);
+}
+
+/* vstring_strcpy - copy string */
+
+VSTRING *vstring_strcpy(VSTRING *vp, const char *src)
+{
+    VSTRING_RESET(vp);
+
+    while (*src) {
+	VSTRING_ADDCH(vp, *src);
+	src++;
+    }
+    VSTRING_TERMINATE(vp);
+    return (vp);
+}
+
+/* vstring_strncpy - copy string of limited length */
+
+VSTRING *vstring_strncpy(VSTRING *vp, const char *src, ssize_t len)
+{
+    VSTRING_RESET(vp);
+
+    while (len-- > 0 && *src) {
+	VSTRING_ADDCH(vp, *src);
+	src++;
+    }
+    VSTRING_TERMINATE(vp);
+    return (vp);
+}
+
+/* vstring_strcat - append string */
+
+VSTRING *vstring_strcat(VSTRING *vp, const char *src)
+{
+    while (*src) {
+	VSTRING_ADDCH(vp, *src);
+	src++;
+    }
+    VSTRING_TERMINATE(vp);
+    return (vp);
+}
+
+/* vstring_strncat - append string of limited length */
+
+VSTRING *vstring_strncat(VSTRING *vp, const char *src, ssize_t len)
+{
+    while (len-- > 0 && *src) {
+	VSTRING_ADDCH(vp, *src);
+	src++;
+    }
+    VSTRING_TERMINATE(vp);
+    return (vp);
+}
+
+/* vstring_memcpy - copy buffer of limited length */
+
+VSTRING *vstring_memcpy(VSTRING *vp, const char *src, ssize_t len)
+{
+    VSTRING_RESET(vp);
+
+    VSTRING_SPACE(vp, len);
+    memcpy(vstring_str(vp), src, len);
+    VSTRING_AT_OFFSET(vp, len);
+    return (vp);
+}
+
+/* vstring_memcat - append buffer of limited length */
+
+VSTRING *vstring_memcat(VSTRING *vp, const char *src, ssize_t len)
+{
+    VSTRING_SPACE(vp, len);
+    memcpy(vstring_end(vp), src, len);
+    len += VSTRING_LEN(vp);
+    VSTRING_AT_OFFSET(vp, len);
+    return (vp);
+}
+
+/* vstring_memchr - locate byte in buffer */
+
+char   *vstring_memchr(VSTRING *vp, int ch)
+{
+    unsigned char *cp;
+
+    for (cp = (unsigned char *) vstring_str(vp); cp < (unsigned char *) vstring_end(vp); cp++)
+	if (*cp == ch)
+	    return ((char *) cp);
+    return (0);
+}
+
+/* vstring_insert - insert text into string */
+
+VSTRING *vstring_insert(VSTRING *vp, ssize_t start, const char *buf, ssize_t len)
+{
+    ssize_t new_len;
+
+    /*
+     * Sanity check.
+     */
+    if (start < 0 || start >= VSTRING_LEN(vp))
+	msg_panic("vstring_insert: bad start %ld", (long) start);
+    if (len < 0)
+	msg_panic("vstring_insert: bad length %ld", (long) len);
+
+    /*
+     * Move the existing content and copy the new content.
+     */
+    new_len = VSTRING_LEN(vp) + len;
+    VSTRING_SPACE(vp, len);
+    memmove(vstring_str(vp) + start + len, vstring_str(vp) + start,
+	    VSTRING_LEN(vp) - start);
+    memcpy(vstring_str(vp) + start, buf, len);
+    VSTRING_AT_OFFSET(vp, new_len);
+    VSTRING_TERMINATE(vp);
+    return (vp);
+}
+
+/* vstring_prepend - prepend text to string */
+
+VSTRING *vstring_prepend(VSTRING *vp, const char *buf, ssize_t len)
+{
+    ssize_t new_len;
+
+    /*
+     * Sanity check.
+     */
+    if (len < 0)
+	msg_panic("vstring_prepend: bad length %ld", (long) len);
+
+    /*
+     * Move the existing content and copy the new content.
+     */
+    new_len = VSTRING_LEN(vp) + len;
+    VSTRING_SPACE(vp, len);
+    memmove(vstring_str(vp) + len, vstring_str(vp), VSTRING_LEN(vp));
+    memcpy(vstring_str(vp), buf, len);
+    VSTRING_AT_OFFSET(vp, new_len);
+    VSTRING_TERMINATE(vp);
+    return (vp);
+}
+
+/* vstring_export - VSTRING to bare string */
+
+char   *vstring_export(VSTRING *vp)
+{
+    char   *cp;
+
+    cp = (char *) vp->vbuf.data;
+    vp->vbuf.data = 0;
+    myfree((void *) vp);
+    return (cp);
+}
+
+/* vstring_import - bare string to vstring */
+
+VSTRING *vstring_import(char *str)
+{
+    VSTRING *vp;
+    ssize_t len;
+
+    vp = (VSTRING *) mymalloc(sizeof(*vp));
+    len = strlen(str);
+    vp->vbuf.flags = 0;
+    vp->vbuf.len = 0;
+    vp->vbuf.data = (unsigned char *) str;
+    vp->vbuf.len = len + 1;
+    VSTRING_AT_OFFSET(vp, len);
+    vp->vbuf.get_ready = vstring_buf_get_ready;
+    vp->vbuf.put_ready = vstring_buf_put_ready;
+    vp->vbuf.space = vstring_buf_space;
+    return (vp);
+}
+
+/* vstring_sprintf - formatted string */
+
+VSTRING *vstring_sprintf(VSTRING *vp, const char *format,...)
+{
+    va_list ap;
+
+    va_start(ap, format);
+    vp = vstring_vsprintf(vp, format, ap);
+    va_end(ap);
+    return (vp);
+}
+
+/* vstring_vsprintf - format string, vsprintf-like interface */
+
+VSTRING *vstring_vsprintf(VSTRING *vp, const char *format, va_list ap)
+{
+    VSTRING_RESET(vp);
+    vbuf_print(&vp->vbuf, format, ap);
+    VSTRING_TERMINATE(vp);
+    return (vp);
+}
+
+/* vstring_sprintf_append - append formatted string */
+
+VSTRING *vstring_sprintf_append(VSTRING *vp, const char *format,...)
+{
+    va_list ap;
+
+    va_start(ap, format);
+    vp = vstring_vsprintf_append(vp, format, ap);
+    va_end(ap);
+    return (vp);
+}
+
+/* vstring_vsprintf_append - format + append string, vsprintf-like interface */
+
+VSTRING *vstring_vsprintf_append(VSTRING *vp, const char *format, va_list ap)
+{
+    vbuf_print(&vp->vbuf, format, ap);
+    VSTRING_TERMINATE(vp);
+    return (vp);
+}
+
+/* vstring_sprintf_prepend - format + prepend string, vsprintf-like interface */
+
+VSTRING *vstring_sprintf_prepend(VSTRING *vp, const char *format,...)
+{
+    va_list ap;
+    ssize_t old_len = VSTRING_LEN(vp);
+    ssize_t result_len;
+
+    /* Construct: old|new|free */
+    va_start(ap, format);
+    vp = vstring_vsprintf_append(vp, format, ap);
+    va_end(ap);
+    result_len = VSTRING_LEN(vp);
+
+    /* Construct: old|new|old|free */
+    VSTRING_SPACE(vp, old_len);
+    vstring_memcat(vp, vstring_str(vp), old_len);
+
+    /* Construct: new|old|free */
+    memmove(vstring_str(vp), vstring_str(vp) + old_len, result_len);
+    VSTRING_AT_OFFSET(vp, result_len);
+    VSTRING_TERMINATE(vp);
+    return (vp);
+}
+
+#ifdef TEST
+
+ /*
+  * Test program - concatenate all command-line arguments into one string.
+  */
+#include <stdio.h>
+
+int     main(int argc, char **argv)
+{
+    VSTRING *vp = vstring_alloc(1);
+    int     n;
+
+    /*
+     * Report the location of the gratuitous null terminator.
+     */
+    for (n = 1; n <= 5; n++) {
+	VSTRING_ADDCH(vp, 'x');
+	printf("payload/buffer size %d/%ld, strlen() %ld\n",
+	       n, (long) (vp)->vbuf.len, (long) strlen(vstring_str(vp)));
+    }
+
+    VSTRING_RESET(vp);
+    while (argc-- > 0) {
+	vstring_strcat(vp, *argv++);
+	vstring_strcat(vp, ".");
+    }
+    printf("argv concatenated: %s\n", vstring_str(vp));
+    vstring_free(vp);
+    return (0);
+}
+
+#endif