Rename target_phys_addr_t to hwaddr

[mirror_qemu.git] / HACKING

diff --git a/HACKING b/HACKING
index da0c1e84e63465c00664c64b8a5edda3083348e0..89a6b3ad444436732c2bae557f6e37ca5b01782a 100644 (file)
--- a/HACKING
+++ b/HACKING
@@ -32,7 +32,7 @@ mandatory for VMState fields.
 
 Don't use Linux kernel internal types like u32, __u32 or __le32.
 
-Use target_phys_addr_t for guest physical addresses except pcibus_t
+Use hwaddr for guest physical addresses except pcibus_t
 for PCI addresses.  In addition, ram_addr_t is a QEMU internal address
 space that maps guest RAM physical addresses into an intermediate
 address space that can map to host virtual address spaces.  Generally
@@ -77,12 +77,49 @@ avoided.
 
 Use of the malloc/free/realloc/calloc/valloc/memalign/posix_memalign
 APIs is not allowed in the QEMU codebase. Instead of these routines,
-use the replacement qemu_malloc/qemu_mallocz/qemu_realloc/qemu_free or
-qemu_vmalloc/qemu_memalign/qemu_vfree APIs.
+use the GLib memory allocation routines g_malloc/g_malloc0/g_new/
+g_new0/g_realloc/g_free or QEMU's qemu_vmalloc/qemu_memalign/qemu_vfree
+APIs.
 
-Please note that NULL check for the qemu_malloc result is redundant and
-that qemu_malloc() call with zero size is not allowed.
+Please note that g_malloc will exit on allocation failure, so there
+is no need to test for failure (as you would have to with malloc).
+Calling g_malloc with a zero size is valid and will return NULL.
 
 Memory allocated by qemu_vmalloc or qemu_memalign must be freed with
 qemu_vfree, since breaking this will cause problems on Win32 and user
 emulators.
+
+4. String manipulation
+
+Do not use the strncpy function.  As mentioned in the man page, it does *not*
+guarantee a NULL-terminated buffer, which makes it extremely dangerous to use.
+It also zeros trailing destination bytes out to the specified length.  Instead,
+use this similar function when possible, but note its different signature:
+void pstrcpy(char *dest, int dest_buf_size, const char *src)
+
+Don't use strcat because it can't check for buffer overflows, but:
+char *pstrcat(char *buf, int buf_size, const char *s)
+
+The same limitation exists with sprintf and vsprintf, so use snprintf and
+vsnprintf.
+
+QEMU provides other useful string functions:
+int strstart(const char *str, const char *val, const char **ptr)
+int stristart(const char *str, const char *val, const char **ptr)
+int qemu_strnlen(const char *s, int max_len)
+
+There are also replacement character processing macros for isxyz and toxyz,
+so instead of e.g. isalnum you should use qemu_isalnum.
+
+Because of the memory management rules, you must use g_strdup/g_strndup
+instead of plain strdup/strndup.
+
+5. Printf-style functions
+
+Whenever you add a new printf-style function, i.e., one with a format
+string argument and following "..." in its prototype, be sure to use
+gcc's printf attribute directive in the prototype.
+
+This makes it so gcc's -Wformat and -Wformat-security options can do
+their jobs and cross-check format strings with the number and types
+of arguments.