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1 /* Append new section.
2    Copyright (C) 1998,1999,2000,2001,2002,2005,2009,2014,2015 Red Hat, Inc.
3    This file is part of elfutils.
4    Written by Ulrich Drepper <drepper@redhat.com>, 1998.
5 
6    This file is free software; you can redistribute it and/or modify
7    it under the terms of either
8 
9      * the GNU Lesser General Public License as published by the Free
10        Software Foundation; either version 3 of the License, or (at
11        your option) any later version
12 
13    or
14 
15      * the GNU General Public License as published by the Free
16        Software Foundation; either version 2 of the License, or (at
17        your option) any later version
18 
19    or both in parallel, as here.
20 
21    elfutils is distributed in the hope that it will be useful, but
22    WITHOUT ANY WARRANTY; without even the implied warranty of
23    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
24    General Public License for more details.
25 
26    You should have received copies of the GNU General Public License and
27    the GNU Lesser General Public License along with this program.  If
28    not, see <http://www.gnu.org/licenses/>.  */
29 
30 #ifdef HAVE_CONFIG_H
31 # include <config.h>
32 #endif
33 
34 #include <assert.h>
35 #include <stdbool.h>
36 #include <stddef.h>
37 #include <stdlib.h>
38 #include <string.h>
39 
40 #include "libelfP.h"
41 
42 
43 Elf_Scn *
elf_newscn(Elf * elf)44 elf_newscn (Elf *elf)
45 {
46   Elf_Scn *result = NULL;
47   bool first = false;
48 
49   if (elf == NULL)
50     return NULL;
51 
52   /* We rely on the prefix of the `elf', `elf32', and `elf64' element
53      being the same.  */
54   assert (offsetof (Elf, state.elf.scns_last)
55 	  == offsetof (Elf, state.elf32.scns_last));
56   assert (offsetof (Elf, state.elf.scns_last)
57 	  == offsetof (Elf, state.elf64.scns_last));
58   assert (offsetof (Elf, state.elf32.scns)
59 	  == offsetof (Elf, state.elf64.scns));
60 
61   rwlock_wrlock (elf->lock);
62 
63  again:
64   if (elf->state.elf.scns_last->cnt < elf->state.elf.scns_last->max)
65     {
66       result = &elf->state.elf.scns_last->data[elf->state.elf.scns_last->cnt];
67 
68       if (++elf->state.elf.scns_last->cnt == 1
69 	  && (elf->state.elf.scns_last
70 	      == (elf->class == ELFCLASS32
71 		  || (offsetof (Elf, state.elf32.scns)
72 		      == offsetof (Elf, state.elf64.scns))
73 		  ? &elf->state.elf32.scns : &elf->state.elf64.scns)))
74 	/* This is zeroth section.  */
75 	first = true;
76       else
77 	{
78 	  assert (elf->state.elf.scns_last->cnt > 1);
79 	  result->index = result[-1].index + 1;
80 	}
81     }
82   else
83     {
84       /* We must allocate a new element.  */
85       Elf_ScnList *newp = NULL;
86 
87       assert (elf->state.elf.scnincr > 0);
88 
89       if (
90 #if SIZE_MAX <= 4294967295U
91 	  likely (elf->state.elf.scnincr
92 		  < SIZE_MAX / 2 / sizeof (Elf_Scn) - sizeof (Elf_ScnList))
93 #else
94 	  1
95 #endif
96 	  )
97       newp = (Elf_ScnList *) calloc (sizeof (Elf_ScnList)
98 				     + ((elf->state.elf.scnincr *= 2)
99 					* sizeof (Elf_Scn)), 1);
100       if (newp == NULL)
101 	{
102 	  __libelf_seterrno (ELF_E_NOMEM);
103 	  goto out;
104 	}
105 
106       result = &newp->data[0];
107 
108       /* One section used.  */
109       ++newp->cnt;
110 
111       /* This is the number of sections we allocated.  */
112       newp->max = elf->state.elf.scnincr;
113 
114       /* Remember the index for the first section in this block.  */
115       newp->data[0].index
116 	= 1 + elf->state.elf.scns_last->data[elf->state.elf.scns_last->max - 1].index;
117 
118       /* Enqueue the new list element.  */
119       elf->state.elf.scns_last = elf->state.elf.scns_last->next = newp;
120     }
121 
122   /* Create a section header for this section.  */
123   if (elf->class == ELFCLASS32)
124     {
125       result->shdr.e32 = (Elf32_Shdr *) calloc (1, sizeof (Elf32_Shdr));
126       if (result->shdr.e32 == NULL)
127 	{
128 	  __libelf_seterrno (ELF_E_NOMEM);
129 	  goto out;
130 	}
131     }
132   else
133     {
134       result->shdr.e64 = (Elf64_Shdr *) calloc (1, sizeof (Elf64_Shdr));
135       if (result->shdr.e64 == NULL)
136 	{
137 	  __libelf_seterrno (ELF_E_NOMEM);
138 	  goto out;
139 	}
140     }
141 
142   result->elf = elf;
143   result->shdr_flags = ELF_F_DIRTY | ELF_F_MALLOCED;
144   result->list = elf->state.elf.scns_last;
145 
146   /* Initialize the data part.  */
147   result->data_read = 1;
148   if (unlikely (first))
149     {
150       /* For the first section we mark the data as already available.  */
151       //result->data_list_rear = &result->data_list;
152       first = false;
153       goto again;
154     }
155 
156   result->flags |= ELF_F_DIRTY;
157 
158  out:
159   rwlock_unlock (elf->lock);
160 
161   return result;
162 }
163