[PATCH 04/19] libctf: low-level list manipulation and helper utilities

[Nick Alcock <nick dot alcock at oracle dot com>]

These utilities are a bit of a ragbag of small things needed by more
than one TU: list manipulation, ELF32->64 translators, routines to look
up strings in string tables, dynamically-allocated string appenders, and
routines to set the specialized errno values previously committed in
<ctf-api.h>.

Notes for reviewers:

The distinction betweern this file and ctf-subr.c is lost in the mists
of time: perhaps it was originally that ctf-subr.c contained nothing but
wrappers.  I am quite amenable to combining the two, and also to
splitting the errno-setting stuff out into ctf-error.c with the error
fetchers.

libctf/
	* ctf-util.c: New file.
	* ctf-impl.h: Add definitions.
---
 libctf/ctf-impl.h |  32 +++++++++
 libctf/ctf-util.c | 176 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 208 insertions(+)
 create mode 100644 libctf/ctf-util.c

diff --git a/libctf/ctf-impl.h b/libctf/ctf-impl.h
index 108c89d2c5..d4d71fbfdc 100644
--- a/libctf/ctf-impl.h
+++ b/libctf/ctf-impl.h
@@ -24,6 +24,13 @@
 #include <sys/errno.h>
 #include <ctf-api.h>
 #include <sys/types.h>
+#include <stdlib.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdint.h>
+#include <limits.h>
+#include <ctype.h>
+#include <gelf.h>
 
 #ifdef	__cplusplus
 extern "C"
@@ -52,6 +59,25 @@ extern "C"
 
 #endif
 
+typedef struct ctf_list
+{
+  struct ctf_list *l_prev;	/* Previous pointer or tail pointer.  */
+  struct ctf_list *l_next;	/* Next pointer or head pointer.  */
+} ctf_list_t;
+
+#define	ctf_list_prev(elem)	((void *)(((ctf_list_t *)(elem))->l_prev))
+#define	ctf_list_next(elem)	((void *)(((ctf_list_t *)(elem))->l_next))
+
+extern void ctf_list_append (ctf_list_t *, void *);
+extern void ctf_list_prepend (ctf_list_t *, void *);
+extern void ctf_list_delete (ctf_list_t *, void *);
+
+extern const char *ctf_strraw (ctf_file_t *, uint32_t);
+extern const char *ctf_strptr (ctf_file_t *, uint32_t);
+
+extern ctf_file_t *ctf_set_open_errno (int *, int);
+extern long ctf_set_errno (ctf_file_t *, int);
+
 extern void *ctf_data_alloc (size_t);
 extern void ctf_data_free (void *, size_t);
 extern void ctf_data_protect (void *, size_t);
@@ -59,9 +85,15 @@ extern void ctf_data_protect (void *, size_t);
 extern void *ctf_alloc (size_t);
 extern void ctf_free (void *, size_t);
 
+extern char *ctf_strdup (const char *);
+extern char *ctf_str_append (char *, const char *);
+extern const char *ctf_strerror (int);
+
 _libctf_printflike_ (1, 2)
 extern void ctf_dprintf (const char *, ...);
 
+extern Elf64_Sym *ctf_sym_to_gelf (const Elf32_Sym *src, Elf64_Sym *dst);
+
 extern int _libctf_debug;	/* debugging messages enabled */
 
 #ifdef	__cplusplus
diff --git a/libctf/ctf-util.c b/libctf/ctf-util.c
new file mode 100644
index 0000000000..a3a8d05dd3
--- /dev/null
+++ b/libctf/ctf-util.c
@@ -0,0 +1,176 @@
+/* Miscellaneous utilities.
+   Copyright (C) 2005-2018 Free Software Foundation, Inc.
+
+   This file is part of libctf.
+
+   libctf is free software; you can redistribute it and/or modify it under
+   the terms of the GNU General Public License as published by the Free
+   Software Foundation; either version 2, or (at your option) any later
+   version.
+
+   This program is distributed in the hope that it will be useful, but
+   WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+   See the GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; see the file COPYING.  If not see
+   <http://www.gnu.org/licenses/>.  */
+
+#include <ctf-impl.h>
+#include <string.h>
+
+/* Simple doubly-linked list append routine.  This implementation assumes that
+   each list element contains an embedded ctf_list_t as the first member.
+   An additional ctf_list_t is used to store the head (l_next) and tail
+   (l_prev) pointers.  The current head and tail list elements have their
+   previous and next pointers set to NULL, respectively.  */
+
+void
+ctf_list_append (ctf_list_t *lp, void *new)
+{
+  ctf_list_t *p = lp->l_prev;	/* p = tail list element.  */
+  ctf_list_t *q = new;		/* q = new list element.  */
+
+  lp->l_prev = q;
+  q->l_prev = p;
+  q->l_next = NULL;
+
+  if (p != NULL)
+    p->l_next = q;
+  else
+    lp->l_next = q;
+}
+
+/* Prepend the specified existing element to the given ctf_list_t.  The
+   existing pointer should be pointing at a struct with embedded ctf_list_t.  */
+
+void
+ctf_list_prepend (ctf_list_t * lp, void *new)
+{
+  ctf_list_t *p = new;		/* p = new list element.  */
+  ctf_list_t *q = lp->l_next;	/* q = head list element.  */
+
+  lp->l_next = p;
+  p->l_prev = NULL;
+  p->l_next = q;
+
+  if (q != NULL)
+    q->l_prev = p;
+  else
+    lp->l_prev = p;
+}
+
+/* Delete the specified existing element from the given ctf_list_t.  The
+   existing pointer should be pointing at a struct with embedded ctf_list_t.  */
+
+void
+ctf_list_delete (ctf_list_t *lp, void *existing)
+{
+  ctf_list_t *p = existing;
+
+  if (p->l_prev != NULL)
+    p->l_prev->l_next = p->l_next;
+  else
+    lp->l_next = p->l_next;
+
+  if (p->l_next != NULL)
+    p->l_next->l_prev = p->l_prev;
+  else
+    lp->l_prev = p->l_prev;
+}
+
+/* Convert a 32-bit ELF symbol into GElf (Elf64) and return a pointer to it.  */
+
+Elf64_Sym *
+ctf_sym_to_gelf (const Elf32_Sym *src, Elf64_Sym *dst)
+{
+  dst->st_name = src->st_name;
+  dst->st_value = src->st_value;
+  dst->st_size = src->st_size;
+  dst->st_info = src->st_info;
+  dst->st_other = src->st_other;
+  dst->st_shndx = src->st_shndx;
+
+  return dst;
+}
+
+/* Convert an encoded CTF string name into a pointer to a C string by looking
+  up the appropriate string table buffer and then adding the offset.  */
+
+const char *
+ctf_strraw (ctf_file_t *fp, uint32_t name)
+{
+  ctf_strs_t *ctsp = &fp->ctf_str[CTF_NAME_STID (name)];
+
+  if (ctsp->cts_strs != NULL && CTF_NAME_OFFSET (name) < ctsp->cts_len)
+    return (ctsp->cts_strs + CTF_NAME_OFFSET (name));
+
+  /* String table not loaded or corrupt offset.  */
+  return NULL;
+}
+
+const char *
+ctf_strptr (ctf_file_t *fp, uint32_t name)
+{
+  const char *s = ctf_strraw (fp, name);
+  return (s != NULL ? s : "(?)");
+}
+
+/* Same as strdup(3C), but use ctf_alloc() to do the memory allocation. */
+
+char *
+ctf_strdup (const char *s1)
+{
+  char *s2 = ctf_alloc (strlen (s1) + 1);
+
+  if (s2 != NULL)
+    (void) strcpy (s2, s1);
+
+  return s2;
+}
+
+/* A string appender working on dynamic strings.  */
+
+char *
+ctf_str_append (char *s, const char *append)
+{
+  size_t s_len = 0;
+
+  if (append == NULL)
+    return s;
+
+  if (s != NULL)
+    s_len = strlen (s);
+
+  size_t append_len = strlen (append);
+
+  if ((s = realloc (s, s_len + append_len + 1)) == NULL)
+    return NULL;
+
+  memcpy (s + s_len, append, append_len);
+  s[s_len + append_len] = '\0';
+
+  return s;
+}
+
+/* Store the specified error code into errp if it is non-NULL, and then
+   return NULL for the benefit of the caller.  */
+
+ctf_file_t *
+ctf_set_open_errno (int *errp, int error)
+{
+  if (errp != NULL)
+    *errp = error;
+  return NULL;
+}
+
+/* Store the specified error code into the CTF container, and then return
+   CTF_ERR for the benefit of the caller. */
+
+long
+ctf_set_errno (ctf_file_t * fp, int err)
+{
+  fp->ctf_errno = err;
+  return CTF_ERR;
+}
-- 
2.21.0.237.gd0cfaa883d