add hg and python

1 files changed, 93 insertions, 0 deletions

diff --git a/sys/src/cmd/python/Python/mysnprintf.c b/sys/src/cmd/python/Python/mysnprintf.c
new file mode 100644
index 000000000..4d3770d89
--- /dev/null
+++ b/sys/src/cmd/python/Python/mysnprintf.c
@@ -0,0 +1,93 @@
+#include "Python.h"
+#include <ctype.h>
+
+/* snprintf() wrappers.  If the platform has vsnprintf, we use it, else we
+   emulate it in a half-hearted way.  Even if the platform has it, we wrap
+   it because platforms differ in what vsnprintf does in case the buffer
+   is too small:  C99 behavior is to return the number of characters that
+   would have been written had the buffer not been too small, and to set
+   the last byte of the buffer to \0.  At least MS _vsnprintf returns a
+   negative value instead, and fills the entire buffer with non-\0 data.
+
+   The wrappers ensure that str[size-1] is always \0 upon return.
+
+   PyOS_snprintf and PyOS_vsnprintf never write more than size bytes
+   (including the trailing '\0') into str.
+
+   If the platform doesn't have vsnprintf, and the buffer size needed to
+   avoid truncation exceeds size by more than 512, Python aborts with a
+   Py_FatalError.
+
+   Return value (rv):
+
+	When 0 <= rv < size, the output conversion was unexceptional, and
+	rv characters were written to str (excluding a trailing \0 byte at
+	str[rv]).
+
+	When rv >= size, output conversion was truncated, and a buffer of
+	size rv+1 would have been needed to avoid truncation.  str[size-1]
+	is \0 in this case.
+
+	When rv < 0, "something bad happened".  str[size-1] is \0 in this
+	case too, but the rest of str is unreliable.  It could be that
+	an error in format codes was detected by libc, or on platforms
+	with a non-C99 vsnprintf simply that the buffer wasn't big enough
+	to avoid truncation, or on platforms without any vsnprintf that
+	PyMem_Malloc couldn't obtain space for a temp buffer.
+
+   CAUTION:  Unlike C99, str != NULL and size > 0 are required.
+*/
+
+int
+PyOS_snprintf(char *str, size_t size, const  char  *format, ...)
+{
+	int rc;
+	va_list va;
+
+	va_start(va, format);
+	rc = PyOS_vsnprintf(str, size, format, va);
+	va_end(va);
+	return rc;
+}
+
+int
+PyOS_vsnprintf(char *str, size_t size, const char  *format, va_list va)
+{
+	int len;  /* # bytes written, excluding \0 */
+#ifndef HAVE_SNPRINTF
+	char *buffer;
+#endif
+	assert(str != NULL);
+	assert(size > 0);
+	assert(format != NULL);
+
+#ifdef HAVE_SNPRINTF
+	len = vsnprintf(str, size, format, va);
+#else
+	/* Emulate it. */
+	buffer = PyMem_MALLOC(size + 512);
+	if (buffer == NULL) {
+		len = -666;
+		goto Done;
+	}
+
+	len = vsprintf(buffer, format, va);
+	if (len < 0)
+		/* ignore the error */;
+
+	else if ((size_t)len >= size + 512)
+		Py_FatalError("Buffer overflow in PyOS_snprintf/PyOS_vsnprintf");
+
+	else {
+		const size_t to_copy = (size_t)len < size ?
+					(size_t)len : size - 1;
+		assert(to_copy < size);
+		memcpy(str, buffer, to_copy);
+		str[to_copy] = '\0';
+	}
+	PyMem_FREE(buffer);
+Done:
+#endif
+	str[size-1] = '\0';
+	return len;
+}