diff options
Diffstat (limited to 'Documentation/filesystems')
| -rw-r--r-- | Documentation/filesystems/seq_file.txt | 19 |
1 files changed, 15 insertions, 4 deletions
diff --git a/Documentation/filesystems/seq_file.txt b/Documentation/filesystems/seq_file.txt index 7fb8e6dc62b..b843743aa0b 100644 --- a/Documentation/filesystems/seq_file.txt +++ b/Documentation/filesystems/seq_file.txt @@ -122,8 +122,7 @@ stop() is the place to free it. } Finally, the show() function should format the object currently pointed to -by the iterator for output. It should return zero, or an error code if -something goes wrong. The example module's show() function is: +by the iterator for output. The example module's show() function is: static int ct_seq_show(struct seq_file *s, void *v) { @@ -132,6 +131,12 @@ something goes wrong. The example module's show() function is: return 0; } +If all is well, the show() function should return zero. A negative error +code in the usual manner indicates that something went wrong; it will be +passed back to user space. This function can also return SEQ_SKIP, which +causes the current item to be skipped; if the show() function has already +generated output before returning SEQ_SKIP, that output will be dropped. + We will look at seq_printf() in a moment. But first, the definition of the seq_file iterator is finished by creating a seq_operations structure with the four functions we have just defined: @@ -182,12 +187,18 @@ The first two output a single character and a string, just like one would expect. seq_escape() is like seq_puts(), except that any character in s which is in the string esc will be represented in octal form in the output. -There is also a function for printing filenames: +There is also a pair of functions for printing filenames: int seq_path(struct seq_file *m, struct path *path, char *esc); + int seq_path_root(struct seq_file *m, struct path *path, + struct path *root, char *esc) Here, path indicates the file of interest, and esc is a set of characters -which should be escaped in the output. +which should be escaped in the output. A call to seq_path() will output +the path relative to the current process's filesystem root. If a different +root is desired, it can be used with seq_path_root(). Note that, if it +turns out that path cannot be reached from root, the value of root will be +changed in seq_file_root() to a root which *does* work. Making it all work |