[PATCH v2 1/7] Introduce read_entire_file

Tom Tromey
2020-06-23T13:20:22Z

This adds a new function, read_entire_file, and changes the source
cache to use it. This will be used in a subsequent patch as well.

gdb/ChangeLog
2020-06-22 Tom Tromey <tom@tromey.com>

* utils.h (myread): Don't declare.
* utils.c (myread): Remove.
* source-cache.c (source_cache::get_plain_source_lines): Use
read_entire_file.

gdbsupport/ChangeLog
2020-06-22 Tom Tromey <tom@tromey.com>

* filestuff.h (read_entire_file): Declare.
* filestuff.cc (read_entire_file): New function.
---
gdb/ChangeLog | 7 +++++++
gdb/source-cache.c | 14 +++++---------
gdb/utils.c | 22 ----------------------
gdb/utils.h | 2 --
gdbsupport/ChangeLog | 5 +++++
gdbsupport/filestuff.cc | 33 +++++++++++++++++++++++++++++++++
gdbsupport/filestuff.h | 9 +++++++++
7 files changed, 59 insertions(+), 33 deletions(-)

diff --git a/gdb/source-cache.c b/gdb/source-cache.c
index 9196e3a19e3..63e08c3aeb0 100644
--- a/gdb/source-cache.c
+++ b/gdb/source-cache.c
@@ -18,6 +18,7 @@

#include "defs.h"
#include "source-cache.h"
+#include "gdbsupport/filestuff.h"
#include "gdbsupport/scoped_fd.h"
#include "source.h"
#include "cli/cli-style.h"
@@ -56,14 +57,9 @@ source_cache::get_plain_source_lines (struct symtab *s,
if (desc.get () < 0)
perror_with_name (symtab_to_filename_for_display (s));

- struct stat st;
- if (fstat (desc.get (), &st) < 0)
- perror_with_name (symtab_to_filename_for_display (s));
-
- std::string lines;
- lines.resize (st.st_size);
- if (myread (desc.get (), &lines[0], lines.size ()) < 0)
- perror_with_name (symtab_to_filename_for_display (s));
+ time_t file_mtime;
+ std::string lines = read_entire_file (symtab_to_filename_for_display (s),
+ desc.get (), &file_mtime);

time_t mtime = 0;
if (SYMTAB_OBJFILE (s) != NULL && SYMTAB_OBJFILE (s)->obfd != NULL)
@@ -71,7 +67,7 @@ source_cache::get_plain_source_lines (struct symtab *s,
else if (exec_bfd)
mtime = exec_bfd_mtime;

- if (mtime && mtime < st.st_mtime)
+ if (mtime && mtime < file_mtime)
warning (_("Source file is more recent than executable."));

std::vector<off_t> offsets;
diff --git a/gdb/utils.c b/gdb/utils.c
index 102db28787f..023adfae066 100644
--- a/gdb/utils.c
+++ b/gdb/utils.c
@@ -687,28 +687,6 @@ flush_streams ()
gdb_stderr->flush ();
}

-/* My replacement for the read system call.
- Used like `read' but keeps going if `read' returns too soon. */
-
-int
-myread (int desc, char *addr, int len)
-{
- int val;
- int orglen = len;
-
- while (len > 0)
- {
- val = read (desc, addr, len);
- if (val < 0)
- return val;
- if (val == 0)
- return orglen - len;
- len -= val;
- addr += val;
- }
- return orglen;
-}
-
void
print_spaces (int n, struct ui_file *file)
{
diff --git a/gdb/utils.h b/gdb/utils.h
index 3434ff1caa2..d0989204128 100644
--- a/gdb/utils.h
+++ b/gdb/utils.h
@@ -540,8 +540,6 @@ void dummy_obstack_deallocate (void *object, void *data);
extern pid_t wait_to_die_with_timeout (pid_t pid, int *status, int timeout);
#endif

-extern int myread (int, char *, int);
-
/* Resource limits used by getrlimit and setrlimit. */

enum resource_limit_kind
diff --git a/gdbsupport/filestuff.cc b/gdbsupport/filestuff.cc
index 179c4258918..0f0a238beb0 100644
--- a/gdbsupport/filestuff.cc
+++ b/gdbsupport/filestuff.cc
@@ -501,3 +501,36 @@ mkdir_recursive (const char *dir)
component_start = component_end;
}
}
+
+/* See filestuff.h. */
+
+std::string
+read_entire_file (const char *name, int fd, time_t *mtime)
+{
+ struct stat st;
+ if (fstat (fd, &st) < 0)
+ perror_with_name (name);
+ size_t len = st.st_size;
+
+ std::string lines;
+ lines.resize (len);
+ char *addr = &lines[0];
+
+ while (len > 0)
+ {
+ int val = read (fd, addr, len);
+ if (val < 0)
+ perror_with_name (name);
+ if (val == 0)
+ break;
+ len -= val;
+ addr += val;
+ }
+
+ if (mtime != nullptr)
+ *mtime = st.st_mtime;
+
+ /* Just in case we really did end up short. */
+ lines.resize (st.st_size - len);
+ return lines;
+}
diff --git a/gdbsupport/filestuff.h b/gdbsupport/filestuff.h
index e36936a84ce..84924f462e2 100644
--- a/gdbsupport/filestuff.h
+++ b/gdbsupport/filestuff.h
@@ -139,4 +139,13 @@ extern bool is_regular_file (const char *name, int *errno_ptr);

extern bool mkdir_recursive (const char *dir);

+/* Read and return the entire contents of a file. The file must
+ already be open on FD. NAME is the file name it is used when
+ reporting errors, which is done by throwing an exception. The
+ mtime of the file is optionally stored in *MTIME; if MTIME is
+ nullptr, this is ignored. */
+
+extern std::string read_entire_file (const char *name, int fd,
+ time_t *mtime = nullptr);
+
#endif /* COMMON_FILESTUFF_H */
--
2.17.2