seq_file: Rename seq_overflow() to seq_has_overflowed() and make public
The return values of seq_printf/puts/putc are frequently misused. Start down a path to remove all the return value uses of these functions. Move the seq_overflow() to a global inlined function called seq_has_overflowed() that can be used by the users of seq_file() calls. Update the documentation to not show return types for seq_printf et al. Add a description of seq_has_overflowed(). Link: http://lkml.kernel.org/p/848ac7e3d1c31cddf638a8526fa3c59fa6fdeb8a.1412031505.git.joe@perches.com Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Joe Perches <joe@perches.com> [ Reworked the original patch from Joe ] Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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3 changed files with 30 additions and 22 deletions
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@ -180,23 +180,19 @@ output must be passed to the seq_file code. Some utility functions have
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been defined which make this task easy.
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Most code will simply use seq_printf(), which works pretty much like
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printk(), but which requires the seq_file pointer as an argument. It is
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common to ignore the return value from seq_printf(), but a function
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producing complicated output may want to check that value and quit if
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something non-zero is returned; an error return means that the seq_file
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buffer has been filled and further output will be discarded.
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printk(), but which requires the seq_file pointer as an argument.
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For straight character output, the following functions may be used:
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int seq_putc(struct seq_file *m, char c);
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int seq_puts(struct seq_file *m, const char *s);
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int seq_escape(struct seq_file *m, const char *s, const char *esc);
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seq_putc(struct seq_file *m, char c);
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seq_puts(struct seq_file *m, const char *s);
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seq_escape(struct seq_file *m, const char *s, const char *esc);
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The first two output a single character and a string, just like one would
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expect. seq_escape() is like seq_puts(), except that any character in s
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which is in the string esc will be represented in octal form in the output.
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There is also a pair of functions for printing filenames:
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There are also a pair of functions for printing filenames:
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int seq_path(struct seq_file *m, struct path *path, char *esc);
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int seq_path_root(struct seq_file *m, struct path *path,
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@ -209,6 +205,14 @@ root is desired, it can be used with seq_path_root(). Note that, if it
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turns out that path cannot be reached from root, the value of root will be
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changed in seq_file_root() to a root which *does* work.
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A function producing complicated output may want to check
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bool seq_has_overflowed(struct seq_file *m);
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and avoid further seq_<output> calls if true is returned.
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A true return from seq_has_overflowed means that the seq_file buffer will
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be discarded and the seq_show function will attempt to allocate a larger
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buffer and retry printing.
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Making it all work
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@ -16,17 +16,6 @@
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#include <asm/uaccess.h>
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#include <asm/page.h>
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/*
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* seq_files have a buffer which can may overflow. When this happens a larger
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* buffer is reallocated and all the data will be printed again.
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* The overflow state is true when m->count == m->size.
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*/
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static bool seq_overflow(struct seq_file *m)
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{
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return m->count == m->size;
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}
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static void seq_set_overflow(struct seq_file *m)
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{
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m->count = m->size;
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@ -124,7 +113,7 @@ static int traverse(struct seq_file *m, loff_t offset)
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error = 0;
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m->count = 0;
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}
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if (seq_overflow(m))
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if (seq_has_overflowed(m))
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goto Eoverflow;
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if (pos + m->count > offset) {
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m->from = offset - pos;
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@ -267,7 +256,7 @@ Fill:
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break;
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}
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err = m->op->show(m, p);
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if (seq_overflow(m) || err) {
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if (seq_has_overflowed(m) || err) {
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m->count = offs;
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if (likely(err <= 0))
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break;
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@ -42,6 +42,21 @@ struct seq_operations {
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#define SEQ_SKIP 1
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/**
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* seq_has_overflowed - check if the buffer has overflowed
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* @m: the seq_file handle
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*
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* seq_files have a buffer which may overflow. When this happens a larger
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* buffer is reallocated and all the data will be printed again.
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* The overflow state is true when m->count == m->size.
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*
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* Returns true if the buffer received more than it can hold.
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*/
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static inline bool seq_has_overflowed(struct seq_file *m)
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{
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return m->count == m->size;
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}
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/**
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* seq_get_buf - get buffer to write arbitrary data to
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* @m: the seq_file handle
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