+++ /dev/null
-1. Preprocessor
-
-For variadic macros, stick with this C99-like syntax:
-
-#define DPRINTF(fmt, ...) \
- do { printf("IRQ: " fmt, ## __VA_ARGS__); } while (0)
-
-2. C types
-
-It should be common sense to use the right type, but we have collected
-a few useful guidelines here.
-
-2.1. Scalars
-
-If you're using "int" or "long", odds are good that there's a better type.
-If a variable is counting something, it should be declared with an
-unsigned type.
-
-If it's host memory-size related, size_t should be a good choice (use
-ssize_t only if required). Guest RAM memory offsets must use ram_addr_t,
-but only for RAM, it may not cover whole guest address space.
-
-If it's file-size related, use off_t.
-If it's file-offset related (i.e., signed), use off_t.
-If it's just counting small numbers use "unsigned int";
-(on all but oddball embedded systems, you can assume that that
-type is at least four bytes wide).
-
-In the event that you require a specific width, use a standard type
-like int32_t, uint32_t, uint64_t, etc. The specific types are
-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
-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
-speaking, the size of guest memory can always fit into ram_addr_t but
-it would not be correct to store an actual guest physical address in a
-ram_addr_t.
-
-Use target_ulong (or abi_ulong) for CPU virtual addresses, however
-devices should not need to use target_ulong.
-
-Of course, take all of the above with a grain of salt. If you're about
-to use some system interface that requires a type like size_t, pid_t or
-off_t, use matching types for any corresponding variables.
-
-Also, if you try to use e.g., "unsigned int" as a type, and that
-conflicts with the signedness of a related variable, sometimes
-it's best just to use the *wrong* type, if "pulling the thread"
-and fixing all related variables would be too invasive.
-
-Finally, while using descriptive types is important, be careful not to
-go overboard. If whatever you're doing causes warnings, or requires
-casts, then reconsider or ask for help.
-
-2.2. Pointers
-
-Ensure that all of your pointers are "const-correct".
-Unless a pointer is used to modify the pointed-to storage,
-give it the "const" attribute. That way, the reader knows
-up-front that this is a read-only pointer. Perhaps more
-importantly, if we're diligent about this, when you see a non-const
-pointer, you're guaranteed that it is used to modify the storage
-it points to, or it is aliased to another pointer that is.
-
-2.3. Typedefs
-Typedefs are used to eliminate the redundant 'struct' keyword.
-
-2.4. Reserved namespaces in C and POSIX
-Underscore capital, double underscore, and underscore 't' suffixes should be
-avoided.
-
-3. Low level memory management
-
-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.
-
-Please note that NULL check for the qemu_malloc result is redundant and
-that qemu_malloc() call with zero size is not allowed.
-
-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. According to the man page, it does
-*not* guarantee a NULL-terminated buffer, which makes it extremely dangerous
-to use. Instead, use functionally equivalent function:
-void pstrcpy(char *buf, int buf_size, const char *str)
-
-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 qemu_strdup/qemu_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.
-
-Currently many functions in QEMU are not following this rule but
-patches to add the attribute would be very much appreciated.
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