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libs/libc/stdio/lib_getdelim.c: Make getdelim() behave per specification on OpenGroup.org. Specificailly, needs to reallocate buffer if more data is received than will fit.

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This commit is contained in:
Gregory Nutt 2019-11-13 09:01:52 -06:00
parent 9b75ef06ea
commit 675bf4e9b7
1 changed files with 50 additions and 14 deletions
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64
libs/libc/stdio/lib_getdelim.c
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@ -61,6 +61,8 @@
# define EOLCH '/n'
#endif
#define BUFSIZE_INCR 32
/****************************************************************************
* Public Functions
****************************************************************************/
@ -86,7 +88,7 @@
* by malloc() or the object will be reallocated as if by realloc(),
* respectively, such that the object is large enough to hold the
* characters to be written to it, including the terminating NUL, and
* *n will be set to the new size. If the object was allocated, or if
* *n will be set to the new size. If the object was allocated, or if
* the reallocation operation moved the object, *lineptr will be
* updated to point to the new object or new location. The characters
* read, including any delimiter, will be stored in the object, and a
@ -99,6 +101,7 @@ ssize_t getdelim(FAR char **lineptr, size_t *n, int delimiter,
{
FAR char *dest;
size_t bufsize;
size_t maxcopy;
ssize_t ncopied;
int ch;
int ret;
@ -116,7 +119,18 @@ ssize_t getdelim(FAR char **lineptr, size_t *n, int delimiter,
bufsize = *n;
if (bufsize == 0)
{
return 0;
/* Pick an initial buffer size */
bufsize = BUFSIZE_INCR;
*n = BUFSIZE_INCR;
/* Free any mystery buffer. It will be reallocated below. */
if (*lineptr != NULL)
{
lib_free(*lineptr);
*lineptr = NULL;
}
}
/* If *lineptr is a NULL pointer, then allocate *lineptr with size *n */
@ -134,29 +148,51 @@ ssize_t getdelim(FAR char **lineptr, size_t *n, int delimiter,
*lineptr = dest;
}
/* *lineptr must be point to an object of size at least bufsize bytes. If
* the size of the buffer pointer to lineptr is less than bufsize, then
* reallocate lineptr to bufsize.
*
* REVISIT: How do you get the size of lineptr? Isn't it just plain
* uninitialized memory?
*/
/* Transfer characters until either bufsize characters have been transfer
* or until the delimiter is encountered.
*/
ncopied = 0; /* No bytes have been transferred yet */
bufsize--; /* Reserve a byte for the NUL terminator */
ncopied = 0; /* No bytes have been transferred yet */
maxcopy = bufsize - 1; /* Reserve a byte for the NUL terminator */
do
{
/* If the object pointed to by *lineptr is of insufficient size, the
* object will be reallocated such that the object is large enough to
* hold the characters to be written to it, including the terminating
* NUL, and *n will be set to the new size.
*/
if (ncopied >= maxcopy)
{
FAR char *newbuffer;
bufsize += BUFSIZE_INCR;
newbuffer = (FAR char *)lib_realloc(*lineptr, bufsize);
if (newbuffer == NULL)
{
ret = -ENOMEM;
goto errout;
}
*lineptr = newbuffer;
*n = bufsize;
dest = &newbuffer[ncopied];
maxcopy = bufsize - 1;
}
/* Get the next character and test for EOF */
ch = fgetc(stream);
if (ch == EOF)
{
break;
#ifdef __KERNEL_
return -ENODATA;
#else
/* errno is not set in this case */
return -1;
#endif
}
/* Save the character in the user buffer and increment the number of
@ -170,7 +206,7 @@ ssize_t getdelim(FAR char **lineptr, size_t *n, int delimiter,
* end of the buffer (reserving a byte for the NUL terminator)
*/
}
while (ch != delimiter && ncopied < bufsize);
while (ch != delimiter);
/* Add a NUL terminator character (but don't report this in the number of
* bytes transferred).