tree命令源码分析

为什么选择tree这个命令?

学完APUE的前几章,学完了IO和文件与目录,我们可以做点东西出来了。而借鉴别人的程序就是做出东西的选择之一。

如何下载源代码

http://mama.indstate.edu/users/ice/tree/src/tree-1.7.0.tgz这个链接可以下载到最新的tree源代码,也可以编译成功。

怎么分析源代码

这是个很大的问题,暂时我还没有太多的经验 :(

我们的目的

我们的目的暂时定为搞懂如何遍历所有的目录,并输出。

各部分的作用

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tree-1.7.0
├── color.c
├── hash.c
├── html.c
├── INSTALL
├── json.c
├── LICENSE
├── Makefile
├── strverscmp.c
├── tree.c
├── tree.h
├── unix.c
└── xml.c

核心的就是这几个文件。其中unix.ctree.c是遍历功能的主要函数的所在地。

Makefile

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prefix = /usr

CC=gcc

VERSION=1.7.0
TREE_DEST=tree
BINDIR=${prefix}/bin
MAN=tree.1
MANDIR=${prefix}/man/man1
OBJS=tree.o unix.o html.o xml.o json.o hash.o color.o

# Uncomment options below for your particular OS:

# Linux defaults:
CFLAGS=-ggdb -Wall -DLINUX -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64
#CFLAGS=-O4 -Wall -DLINUX -D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64
#LDFLAGS=-s

#------------------------------------------------------------

all: tree

tree: $(OBJS)
$(CC) $(LDFLAGS) -o $(TREE_DEST) $(OBJS)

$(OBJS): %.o: %.c tree.h
$(CC) $(CFLAGS) -c -o $@ $<

clean:
if [ -x $(TREE_DEST) ]; then rm $(TREE_DEST); fi
if [ -f tree.o ]; then rm *.o; fi
rm -f *~

install: tree
install -d $(BINDIR)
install -d $(MANDIR)
if [ -e $(TREE_DEST) ]; then \
install $(TREE_DEST) $(BINDIR)/$(TREE_DEST); \
fi
install doc/$(MAN) $(MANDIR)/$(MAN)

distclean:
if [ -f tree.o ]; then rm *.o; fi
rm -f *~


dist: distclean
tar zcf ../tree-$(VERSION).tgz -C .. `cat .tarball`

核心程序-遍历目录

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//存储文件和文件夹信息的结构体
struct _info {
char *name; /
char *lnk;
bool isdir;
bool issok;
bool isfifo;
bool isexe;
bool orphan;
mode_t mode, lnkmode;
uid_t uid;
gid_t gid;
off_t size;
time_t atime, ctime, mtime;
dev_t dev;
ino_t inode;
#ifdef __EMX__
long attr;
#endif
char *err;
struct _info **child;
};
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off_t unix_listdir(char *d, int *dt, int *ft, u_long lev, dev_t dev)
{
char *path;
bool nlf = FALSE, colored = FALSE;
long pathsize = 0;
struct _info **dir, **sav;
struct stat sb;
int n, c;

if ((Level >= 0) && (lev > Level)) {
fputc('\n',outfile);
return 0;
}

if (xdev && lev == 0) {
stat(d,&sb);
dev = sb.st_dev;
}

sav = dir = read_dir(d,&n);
if (!dir && n) {
fprintf(outfile," [error opening dir]\n");
return 0;
}
if (!n) {
fputc('\n', outfile);
free_dir(sav);
return 0;
}
if (flimit > 0 && n > flimit) {
fprintf(outfile," [%d entries exceeds filelimit, not opening dir]\n",n);
free_dir(sav);
return 0;
}

if (cmpfunc) qsort(dir,n,sizeof(struct _info *), cmpfunc);
if (lev >= maxdirs-1) {
dirs = xrealloc(dirs,sizeof(int) * (maxdirs += 1024));
memset(dirs+(maxdirs-1024), 0, sizeof(int) * 1024);
}
dirs[lev] = 1;
if (!*(dir+1)) dirs[lev] = 2;
fprintf(outfile,"\n");

path = malloc(pathsize=4096);

while(*dir) {
if (!noindent) indent(lev);

fillinfo(path,*dir);
if (path[0] == ' ') {
path[0] = '[';
fprintf(outfile, "%s] ",path);
}

if (colorize) {
if ((*dir)->lnk && linktargetcolor) colored = color((*dir)->lnkmode,(*dir)->name,(*dir)->orphan,FALSE);
else colored = color((*dir)->mode,(*dir)->name,(*dir)->orphan,FALSE);
}

if (fflag) {
if (sizeof(char) * (strlen(d)+strlen((*dir)->name)+2) > pathsize)
path=xrealloc(path,pathsize=(sizeof(char) * (strlen(d)+strlen((*dir)->name)+1024)));
if (!strcmp(d,"/")) sprintf(path,"%s%s",d,(*dir)->name);
else sprintf(path,"%s/%s",d,(*dir)->name);
} else {
if (sizeof(char) * (strlen((*dir)->name)+1) > pathsize)
path=xrealloc(path,pathsize=(sizeof(char) * (strlen((*dir)->name)+1024)));
sprintf(path,"%s",(*dir)->name);
}

printit(path);

if (colored) fprintf(outfile,"%s",endcode);
if (Fflag && !(*dir)->lnk) {
if ((c = Ftype((*dir)->mode))) fputc(c, outfile);
}

if ((*dir)->lnk) {
fprintf(outfile," -> ");
if (colorize) colored = color((*dir)->lnkmode,(*dir)->lnk,(*dir)->orphan,TRUE);
printit((*dir)->lnk);
if (colored) fprintf(outfile,"%s",endcode);
if (Fflag) {
if ((c = Ftype((*dir)->lnkmode))) fputc(c, outfile);
}
}

if ((*dir)->isdir) {
if ((*dir)->lnk) {
if (lflag && !(xdev && dev != (*dir)->dev)) {
if (findino((*dir)->inode,(*dir)->dev)) {
fprintf(outfile," [recursive, not followed]");
} else {
saveino((*dir)->inode, (*dir)->dev);
if (*(*dir)->lnk == '/')
listdir((*dir)->lnk,dt,ft,lev+1,dev);
else {
if (strlen(d)+strlen((*dir)->lnk)+2 > pathsize) path=xrealloc(path,pathsize=(strlen(d)+strlen((*dir)->name)+1024));
if (fflag && !strcmp(d,"/")) sprintf(path,"%s%s",d,(*dir)->lnk);
else sprintf(path,"%s/%s",d,(*dir)->lnk);
listdir(path,dt,ft,lev+1,dev);
}
nlf = TRUE;
}
}
} else if (!(xdev && dev != (*dir)->dev)) {
if (strlen(d)+strlen((*dir)->name)+2 > pathsize) path=xrealloc(path,pathsize=(strlen(d)+strlen((*dir)->name)+1024));
if (fflag && !strcmp(d,"/")) sprintf(path,"%s%s",d,(*dir)->name);
else sprintf(path,"%s/%s",d,(*dir)->name);
saveino((*dir)->inode, (*dir)->dev);
listdir(path,dt,ft,lev+1,dev);
nlf = TRUE;
}
*dt += 1;
} else *ft += 1;
if (*(dir+1) && !*(dir+2)) dirs[lev] = 2;
if (nlf) nlf = FALSE;
else fprintf(outfile,"\n");
dir++;
}
dirs[lev] = 0;
free(path);
free_dir(sav);
return 0;
}

off_t unix_rlistdir(char *d, int *dt, int *ft, u_long lev, dev_t dev)
{
struct _info **dir;
off_t size = 0;
char *err;

dir = getfulltree(d, lev, dev, &size, &err);

memset(dirs, 0, sizeof(int) * maxdirs);

r_listdir(dir, d, dt, ft, lev);

return size;
}

void r_listdir(struct _info **dir, char *d, int *dt, int *ft, u_long lev)
{
char *path;
long pathsize = 0;
struct _info **sav = dir;
bool nlf = FALSE, colored = FALSE;
int c;

if (dir == NULL) return;

dirs[lev] = 1;
if (!*(dir+1)) dirs[lev] = 2;
fprintf(outfile,"\n");

path = malloc(pathsize=4096);

while(*dir) {
if (!noindent) indent(lev);

fillinfo(path,*dir);
if (path[0] == ' ') {
path[0] = '[';
fprintf(outfile, "%s] ",path);
}

if (colorize) {
if ((*dir)->lnk && linktargetcolor) colored = color((*dir)->lnkmode,(*dir)->name,(*dir)->orphan,FALSE);
else colored = color((*dir)->mode,(*dir)->name,(*dir)->orphan,FALSE);
}

if (fflag) {
if (sizeof(char) * (strlen(d)+strlen((*dir)->name)+2) > pathsize)
path=xrealloc(path,pathsize=(sizeof(char) * (strlen(d)+strlen((*dir)->name)+1024)));
if (!strcmp(d,"/")) sprintf(path,"%s%s",d,(*dir)->name);
else sprintf(path,"%s/%s",d,(*dir)->name);
} else {
if (sizeof(char) * (strlen((*dir)->name)+1) > pathsize)
path=xrealloc(path,pathsize=(sizeof(char) * (strlen((*dir)->name)+1024)));
sprintf(path,"%s",(*dir)->name);
}

printit(path);

if (colored) fprintf(outfile,"%s",endcode);
if (Fflag && !(*dir)->lnk) {
if ((c = Ftype((*dir)->mode))) fputc(c, outfile);
}

if ((*dir)->lnk) {
fprintf(outfile," -> ");
if (colorize) colored = color((*dir)->lnkmode,(*dir)->lnk,(*dir)->orphan,TRUE);
printit((*dir)->lnk);
if (colored) fprintf(outfile,"%s",endcode);
if (Fflag) {
if ((c = Ftype((*dir)->lnkmode))) fputc(c, outfile);
}
}

if ((*dir)->err) {
fprintf(outfile," [%s]", (*dir)->err);
free((*dir)->err);
(*dir)->err = NULL;
}
if ((*dir)->child) {
if (fflag) {
if (strlen(d)+strlen((*dir)->name)+2 > pathsize) path=xrealloc(path,pathsize=(strlen(d)+strlen((*dir)->name)+1024));
if (!strcmp(d,"/")) sprintf(path,"%s%s",d,(*dir)->name);
else sprintf(path,"%s/%s",d,(*dir)->name);
}
r_listdir((*dir)->child, fflag? path : NULL, dt, ft, lev+1);
nlf = TRUE;
*dt += 1;
} else {
if ((*dir)->isdir) *dt += 1;
else *ft += 1;
}

if (*(dir+1) && !*(dir+2)) dirs[lev] = 2;
if (nlf) nlf = FALSE;
else fprintf(outfile,"\n");
dir++;
}
dirs[lev] = 0;
free(path);
free_dir(sav);
}
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