do early allocation for nonzero size with NULL buffer; cleanup; prettiness

SCCS-vsn: lib/libc/stdio/setvbuf.c 5.4

diff --git a/usr/src/lib/libc/stdio/setvbuf.c b/usr/src/lib/libc/stdio/setvbuf.c
index 4952d69..acf1996 100644 (file)
--- a/usr/src/lib/libc/stdio/setvbuf.c
+++ b/usr/src/lib/libc/stdio/setvbuf.c
@@ -9,7 +9,7 @@
  */
 
 #if defined(LIBC_SCCS) && !defined(lint)
  */
 
 #if defined(LIBC_SCCS) && !defined(lint)

-static char sccsid[] = "@(#)setvbuf.c  5.3 (Berkeley) %G%";
+static char sccsid[] = "@(#)setvbuf.c  5.4 (Berkeley) %G%";

 #endif /* LIBC_SCCS and not lint */
 
 #include <stdio.h>
 #endif /* LIBC_SCCS and not lint */
 
 #include <stdio.h>


@@ -26,8 +26,7 @@ setvbuf(fp, buf, mode, size)
        register int mode;
        register size_t size;
 {
        register int mode;
        register size_t size;
 {

-       if (buf == NULL)
-               size = 0;
+       register int ret, flags;

 
        /*
         * Verify arguments.  The `int' limit on `size' is due to this
 
        /*
         * Verify arguments.  The `int' limit on `size' is due to this


@@ -38,33 +37,54 @@ setvbuf(fp, buf, mode, size)
                return (EOF);
 
        /*
                return (EOF);
 
        /*

-        * Write current buffer, if any; drop read count, if any.
-        * Make sure putc() will not think fp is line buffered.
-        * Free old buffer if it was from malloc().  Clear line and
-        * non buffer flags, and clear malloc flag.
+        * OK so far.  Write current buffer, if any; drop read count, if
+        * any.  Make sure putc() will not think fp is line buffered.  Free
+        * old buffer if it was from malloc().  Clear line and non-buffer
+        * flags, and clear malloc flag.

         */
         */

+       ret = 0;

        (void) __sflush(fp);
        fp->_r = 0;
        fp->_lbfsize = 0;
        (void) __sflush(fp);
        fp->_r = 0;
        fp->_lbfsize = 0;

-       if (fp->_flags & __SMBF)
+       flags = fp->_flags;
+       if (flags & __SMBF)

                free((void *)fp->_bf._base);
                free((void *)fp->_bf._base);

-       fp->_flags &= ~(__SLBF|__SNBF|__SMBF);
+       flags &= ~(__SLBF | __SNBF | __SMBF);
+
+       if (size == 0)
+               buf = NULL;     /* we will make a real one later */
+       else if (buf == NULL) {
+               /*
+                * Caller wants specific buffering mode and size but did
+                * not provide a buffer.  Produce one of the given size.
+                * If that fails, set the size to 0 and continue, so that
+                * we will try again later with a system-supplied size
+                * (failure here is probably from someone with the bogus
+                * idea that larger is always better, asking for many MB),
+                * but return EOF to indicate failure.
+                */
+               if ((buf = malloc(size)) == NULL) {
+                       ret = EOF;
+                       size = 0;
+               } else
+                       flags |= __SMBF;
+       }

 
        /*
 
        /*

-        * Now put back whichever flag is needed, and fix _lbfsize
-        * if line buffered.  Ensure output flush on exit if the
-        * stream will be buffered at all.
+        * Now put back whichever flag is needed, and fix _lbfsize if line
+        * buffered.  Ensure output flush on exit if the stream will be
+        * buffered at all.

         */
        switch (mode) {
 
        case _IONBF:
         */
        switch (mode) {
 
        case _IONBF:

-               fp->_flags |= __SNBF;
+               flags |= __SNBF;

                fp->_bf._base = fp->_p = fp->_nbuf;
                fp->_bf._size = 1;
                break;
 
        case _IOLBF:
                fp->_bf._base = fp->_p = fp->_nbuf;
                fp->_bf._size = 1;
                break;
 
        case _IOLBF:

-               fp->_flags |= __SLBF;
+               flags |= __SLBF;

                fp->_lbfsize = -size;
                /* FALLTHROUGH */
 
                fp->_lbfsize = -size;
                /* FALLTHROUGH */
 


@@ -79,8 +99,9 @@ setvbuf(fp, buf, mode, size)
        /*
         * Patch up write count if necessary.
         */
        /*
         * Patch up write count if necessary.
         */

-       if (fp->_flags & __SWR)
-               fp->_w = fp->_flags & (__SLBF|__SNBF) ? 0 : size;
+       if (flags & __SWR)
+               fp->_w = flags & (__SLBF | __SNBF) ? 0 : size;
+       fp->_flags = flags;

 
 

-       return (0);
+       return (ret);

 }
 }