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Subject[PATCH v2 03/29] modpost: add read_text_file() and get_line() helpers
Date
modpost uses grab_file() to open a file, but it is not suitable for
a text file because the mmap'ed file is not terminated by null byte.
Actually, I see some issues for the use of grab_file().

The new helper, read_text_file() loads the whole file content into a
malloc'ed buffer, and appends a null byte. Then, get_line() reads
each line.

To handle text files, I intend to replace as follows:

grab_file() -> read_text_file()
get_new_line() -> get_line()

Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
---

Changes in v2:
- Iterate in while () {} in case read() returns shorter read bytes

scripts/mod/modpost.c | 46 +++++++++++++++++++++++++++++++++++++++++++
scripts/mod/modpost.h | 2 ++
2 files changed, 48 insertions(+)

diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index af098d7efc22..139b811dc183 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -112,6 +112,52 @@ void *do_nofail(void *ptr, const char *expr)
return ptr;
}

+char *read_text_file(const char *filename)
+{
+ struct stat st;
+ size_t nbytes;
+ int fd;
+ char *buf;
+
+ fd = open(filename, O_RDONLY);
+ if (fd < 0)
+ return NULL;
+
+ if (fstat(fd, &st) < 0)
+ return NULL;
+
+ buf = NOFAIL(malloc(st.st_size + 1));
+
+ nbytes = st.st_size;
+
+ while (nbytes) {
+ ssize_t bytes_read;
+
+ bytes_read = read(fd, buf, nbytes);
+ if (bytes_read < 0) {
+ free(buf);
+ buf = NULL;
+ goto close;
+ }
+
+ nbytes -= bytes_read;
+ }
+ buf[st.st_size] = '\0';
+close:
+ close(fd);
+
+ return buf;
+}
+
+char *get_line(char **stringp)
+{
+ /* do not return the unwanted extra line at EOF */
+ if (*stringp && **stringp == '\0')
+ return NULL;
+
+ return strsep(stringp, "\n");
+}
+
/* A list of all modules we processed */
static struct module *modules;

diff --git a/scripts/mod/modpost.h b/scripts/mod/modpost.h
index bbaf5cc37bfb..dfadaa0c01ec 100644
--- a/scripts/mod/modpost.h
+++ b/scripts/mod/modpost.h
@@ -190,6 +190,8 @@ void add_moddevtable(struct buffer *buf, struct module *mod);
void get_src_version(const char *modname, char sum[], unsigned sumlen);

/* from modpost.c */
+char *read_text_file(const char *filename);
+char *get_line(char **stringp);
void *grab_file(const char *filename, unsigned long *size);
char* get_next_line(unsigned long *pos, void *file, unsigned long size);
void release_file(void *file, unsigned long size);
--
2.25.1
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