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Add comments to all the functions in this file documenting what they're for.
This commit is contained in:
Rob Landley
parent
74bb70cf54
commit
23b61be0df
109
libbb/xfuncs.c
109
libbb/xfuncs.c
@ -11,8 +11,13 @@
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#include "busybox.h"
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/* All the functions starting with "x" call bb_error_msg_and_die() if they
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* fail, so callers never need to check for errors. If it returned, it
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* succeeded. */
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#ifndef DMALLOC
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#ifdef L_xmalloc
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// Die if we can't allocate size bytes of memory.
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void *xmalloc(size_t size)
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{
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void *ptr = malloc(size);
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@ -23,6 +28,9 @@ void *xmalloc(size_t size)
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#endif
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#ifdef L_xrealloc
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// Die if we can't resize previously allocated memory. (This returns a pointer
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// to the new memory, which may or may not be the same as the old memory.
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// It'll copy the contents to a new chunk and free the old one if necessary.)
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void *xrealloc(void *ptr, size_t size)
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{
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ptr = realloc(ptr, size);
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@ -33,6 +41,7 @@ void *xrealloc(void *ptr, size_t size)
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#endif
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#ifdef L_xzalloc
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// Die if we can't allocate and zero size bytes of memory.
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void *xzalloc(size_t size)
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{
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void *ptr = xmalloc(size);
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@ -44,7 +53,8 @@ void *xzalloc(size_t size)
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#endif /* DMALLOC */
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#ifdef L_xstrdup
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char * xstrdup (const char *s)
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// Die if we can't copy a string to freshly allocated memory.
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char * xstrdup(const char *s)
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{
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char *t;
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@ -61,7 +71,9 @@ char * xstrdup (const char *s)
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#endif
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#ifdef L_xstrndup
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char * xstrndup (const char *s, int n)
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// Die if we can't allocate n+1 bytes (space for the null terminator) and copy
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// the (possibly truncated to length n) string into it.
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char * xstrndup(const char *s, int n)
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{
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char *t;
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@ -75,6 +87,8 @@ char * xstrndup (const char *s, int n)
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#endif
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#ifdef L_xfopen
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// Die if we can't open a file and return a FILE * to it.
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// Notice we haven't got xfread(), This is for use with fscanf() and friends.
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FILE *xfopen(const char *path, const char *mode)
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{
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FILE *fp;
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@ -85,13 +99,18 @@ FILE *xfopen(const char *path, const char *mode)
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#endif
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#ifdef L_xopen
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// Die if we can't open an existing file and return an fd.
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int xopen(const char *pathname, int flags)
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{
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if (ENABLE_DEBUG && (flags && O_CREAT))
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bb_error_msg_and_die("xopen() with O_CREAT\n");
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return xopen3(pathname, flags, 0777);
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}
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#endif
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#ifdef L_xopen3
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// Die if we can't open a new file and return an fd.
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int xopen3(const char *pathname, int flags, int mode)
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{
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int ret;
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@ -105,9 +124,7 @@ int xopen3(const char *pathname, int flags, int mode)
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#endif
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#ifdef L_xread
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// Die with an error message if we can't read the entire buffer.
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void xread(int fd, void *buf, size_t count)
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{
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while (count) {
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@ -122,9 +139,7 @@ void xread(int fd, void *buf, size_t count)
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#endif
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#ifdef L_xwrite
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// Die with an error message if we can't write the entire buffer.
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void xwrite(int fd, void *buf, size_t count)
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{
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while (count) {
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@ -139,9 +154,7 @@ void xwrite(int fd, void *buf, size_t count)
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#endif
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#ifdef L_xlseek
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// Die if we can't lseek to the right spot.
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// Die with an error message if we can't lseek to the right spot.
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void xlseek(int fd, off_t offset, int whence)
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{
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if (offset != lseek(fd, offset, whence)) bb_error_msg_and_die("lseek");
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@ -149,6 +162,7 @@ void xlseek(int fd, off_t offset, int whence)
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#endif
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#ifdef L_xread_char
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// Die with an error message if we can't read one character.
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unsigned char xread_char(int fd)
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{
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char tmp;
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@ -160,6 +174,7 @@ unsigned char xread_char(int fd)
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#endif
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#ifdef L_xferror
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// Die with supplied error message if this FILE * has ferror set.
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void xferror(FILE *fp, const char *fn)
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{
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if (ferror(fp)) {
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@ -169,6 +184,7 @@ void xferror(FILE *fp, const char *fn)
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#endif
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#ifdef L_xferror_stdout
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// Die with an error message if stdout has ferror set.
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void xferror_stdout(void)
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{
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xferror(stdout, bb_msg_standard_output);
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@ -176,6 +192,7 @@ void xferror_stdout(void)
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#endif
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#ifdef L_xfflush_stdout
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// Die with an error message if we have trouble flushing stdout.
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void xfflush_stdout(void)
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{
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if (fflush(stdout)) {
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@ -185,7 +202,8 @@ void xfflush_stdout(void)
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#endif
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#ifdef L_spawn
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// This does a fork/exec in one call, using vfork().
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// This does a fork/exec in one call, using vfork(). Return PID of new child,
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// -1 for failure. Runs argv[0], searching path if that has no / in it.
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pid_t spawn(char **argv)
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{
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static int failed;
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@ -211,6 +229,7 @@ pid_t spawn(char **argv)
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#endif
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#ifdef L_xspawn
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// Die with an error message if we can't spawn a child process.
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pid_t xspawn(char **argv)
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{
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pid_t pid = spawn(argv);
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@ -220,6 +239,7 @@ pid_t xspawn(char **argv)
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#endif
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#ifdef L_wait4
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// Wait for the specified child PID to exit, returning child's error return.
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int wait4pid(int pid)
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{
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int status;
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@ -232,11 +252,9 @@ int wait4pid(int pid)
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#endif
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#ifdef L_itoa
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// Largest 32 bit integer is -2 billion plus null terminator.
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// Int should always be 32 bits on a Unix-oid system, see
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// http://www.unix.org/whitepapers/64bit.html
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static char local_buf[12];
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// Convert unsigned integer to ascii, writing into supplied buffer. A
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// truncated result is always null terminated (unless buflen is 0), and
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// contains the first few digits of the result ala strncpy.
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void utoa_to_buf(unsigned n, char *buf, unsigned buflen)
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{
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int i, out = 0;
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@ -254,15 +272,7 @@ void utoa_to_buf(unsigned n, char *buf, unsigned buflen)
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}
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}
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// Note: uses static buffer, calling it twice in a row will overwrite.
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char *utoa(unsigned n)
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{
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utoa_to_buf(n, local_buf, sizeof(local_buf));
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return local_buf;
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}
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// Convert signed integer to ascii, like utoa_to_buf()
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void itoa_to_buf(int n, char *buf, unsigned buflen)
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{
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if (buflen && n<0) {
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@ -273,8 +283,24 @@ void itoa_to_buf(int n, char *buf, unsigned buflen)
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utoa_to_buf((unsigned)n, buf, buflen);
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}
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// Note: uses static buffer, calling it twice in a row will overwrite.
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// The following two functions use a static buffer, so calling either one a
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// second time will overwrite previous results.
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//
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// The largest 32 bit integer is -2 billion plus null terminator, or 12 bytes.
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// Int should always be 32 bits on any remotely Unix-like system, see
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// http://www.unix.org/whitepapers/64bit.html for the reasons why.
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static char local_buf[12];
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// Convert unsigned integer to ascii using a static buffer (returned).
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char *utoa(unsigned n)
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{
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utoa_to_buf(n, local_buf, sizeof(local_buf));
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return local_buf;
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}
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// Convert signed integer to ascii using a static buffer (returned).
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char *itoa(int n)
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{
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itoa_to_buf(n, local_buf, sizeof(local_buf));
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@ -284,11 +310,15 @@ char *itoa(int n)
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#endif
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#ifdef L_setuid
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// Die with an error message if we can't set gid. (Because resource limits may
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// limit this user to a given number of processes, and if that fills up the
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// setgid() will fail and we'll _still_be_root_, which is bad.)
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void xsetgid(gid_t gid)
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{
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if (setgid(gid)) bb_error_msg_and_die("setgid");
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}
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// Die with an error message if we cant' set uid. (See xsetgid() for why.)
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void xsetuid(uid_t uid)
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{
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if (setuid(uid)) bb_error_msg_and_die("setuid");
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@ -296,6 +326,7 @@ void xsetuid(uid_t uid)
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#endif
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#ifdef L_fdlength
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// Return how long the file at fd is, if there's any way to determine it.
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off_t fdlength(int fd)
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{
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off_t bottom = 0, top = 0, pos;
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@ -305,7 +336,8 @@ off_t fdlength(int fd)
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if (ioctl(fd, BLKGETSIZE, &size) >= 0) return size*512;
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// If not, do a binary search for the last location we can read.
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// If not, do a binary search for the last location we can read. (Some
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// block devices don't do BLKGETSIZE right.)
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do {
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char temp;
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@ -334,6 +366,8 @@ off_t fdlength(int fd)
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#endif
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#ifdef L_xasprintf
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// Die with an error message if we can't malloc() enough space and do an
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// sprintf() into that space.
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char *xasprintf(const char *format, ...)
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{
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va_list p;
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@ -362,6 +396,8 @@ char *xasprintf(const char *format, ...)
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#endif
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#ifdef L_xprint_and_close_file
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// Die with an error message if we can't copy an entire FILE * to stdout, then
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// close that file.
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void xprint_and_close_file(FILE *file)
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{
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// copyfd outputs error messages for us.
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@ -372,6 +408,7 @@ void xprint_and_close_file(FILE *file)
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#endif
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#ifdef L_xchdir
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// Die if we can't chdir to a new path.
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void xchdir(const char *path)
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{
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if (chdir(path))
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@ -380,6 +417,7 @@ void xchdir(const char *path)
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#endif
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#ifdef L_warn_opendir
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// Print a warning message if opendir() fails, but don't die.
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DIR *warn_opendir(const char *path)
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{
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DIR *dp;
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@ -393,6 +431,7 @@ DIR *warn_opendir(const char *path)
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#endif
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#ifdef L_xopendir
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// Die with an error message if opendir() fails.
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DIR *xopendir(const char *path)
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{
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DIR *dp;
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@ -405,6 +444,7 @@ DIR *xopendir(const char *path)
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#ifdef L_xdaemon
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#ifndef BB_NOMMU
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// Die with an error message if we can't daemonize.
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void xdaemon(int nochdir, int noclose)
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{
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if (daemon(nochdir, noclose)) bb_perror_msg_and_die("daemon");
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@ -412,14 +452,8 @@ void xdaemon(int nochdir, int noclose)
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#endif
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#endif
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#ifdef L_xbind
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void xbind(int sockfd, struct sockaddr *my_addr, socklen_t addrlen)
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{
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if (bind(sockfd, my_addr, addrlen)) bb_perror_msg_and_die("bind");
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}
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#endif
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#ifdef L_xsocket
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// Die with an error message if we can't open a new socket.
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int xsocket(int domain, int type, int protocol)
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{
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int r = socket(domain, type, protocol);
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@ -430,7 +464,16 @@ int xsocket(int domain, int type, int protocol)
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}
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#endif
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#ifdef L_xbind
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// Die with an error message if we can't bind a socket to an address.
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void xbind(int sockfd, struct sockaddr *my_addr, socklen_t addrlen)
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{
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if (bind(sockfd, my_addr, addrlen)) bb_perror_msg_and_die("bind");
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}
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#endif
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#ifdef L_xlisten
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// Die with an error message if we can't listen for connections on a socket.
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void xlisten(int s, int backlog)
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{
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if (listen(s, backlog)) bb_perror_msg_and_die("listen");
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